Methods for forming peroxyformic acid and uses thereof

ABSTRACT

The present invention relates generally to methods for forming peroxyformic acid, comprising contacting formic acid with hydrogen peroxide. The methods for forming peroxyformic acid can include adding formic acid with a relatively lower concentration of hydrogen peroxide, or adding formic acid to a peroxycarboxylic acid composition or forming composition to react with hydrogen peroxide in the compositions. The present invention also relates to peroxyformic acid formed by the above methods. The present invention further relates to the uses of peroxyformic acid for treating a variety of targets, e.g., target water, including target water used in connection with oil- and gas-field operations. The present invention further relates to methods for reducing or removing H 2 S or iron sulfide in the treated water source, improving clarity of the treated water source, or reducing the total dissolved oxygen or corrosion in the treated water source, using peroxyformic acid, including peroxyformic acid generated in situ.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation Application of U.S. Ser. No. 16/259,009, filedJan. 28, 2019, which is a Continuation Application of U.S. Ser. No.15/730,502, filed Oct. 11, 2017, now U.S. Pat. No. 10,233,149, issuedMar. 19, 2019, which is a Continuation Application of U.S. Ser. No.14/972,308, filed Dec. 17, 2015, now U.S. Pat. No. 9,845,290, issuedDec. 19, 2017, which claims priority under 35 U.S.C. § 119 to U.S.Provisional Application Ser. No. 62/094,056 filed Dec. 18, 2014. Theentire contents of these patent applications are hereby expresslyincorporated herein by reference including, without limitation, thespecification, claims, and abstract, as well as any figures, tables, ordrawings thereof.

FIELD OF THE INVENTION

The present invention relates generally to methods for formingperoxyformic acid, comprising contacting formic acid with a relativelylower concentration of hydrogen peroxide. The present invention furtherrelates to co-formulations for reaction of formic acid (and optionallyother components, such as corrosion inhibitors) with hydrogen peroxide.The present invention also relates to peroxyformic acid formed by thesemethods. The present invention further relates to the uses ofperoxyformic acid for treating a target, e.g., target water, includingtarget water used in connection with oil- and gas-field operations.Other exemplary targets include target water, surface(s) and/or otheritems used in papermaking, textiles, food, or pharmaceutical industry.The present invention further relates to methods for reducing orremoving hydrogen sulfide (H₂S) or iron sulfide in a water source,improving clarity of a water source, or reducing the total dissolvedoxygen or corrosion in a water source, using peroxyformic acid,including peroxyformic acid generated in situ.

BACKGROUND OF THE INVENTION

An increase in both conventional and unconventional oil and gasexploration has created a necessity for technologies that promote waterreuse. Produced water reuse poses numerous challenges that includetreatments for iron sulfide, hydrogen sulfide and microbial reductionamong others.

Peracid use in the oil and gas industry is gaining wide acceptancebecause of the versatility, environmental profile and selectiveness ofthe chemistry. The most commonly used peracid formulation containsperacetic acid (CH₃COOOH) and hydrogen peroxide in equilibrium. Howeverone of the caveats of any peracetic acid, hydrogen peroxide formulationis the formation of oxygen in the treatment vessel. Oxygen productionincreases the risk of corrosion significantly. Therefore, the use ofsuch formulations has been limited to onshore as well as open systems.Thus there is a need to seek alternative ways to treat the water in oiland gas industry that has the same or better performance as peraceticacid systems, but reduce or minimize oxygen related corrosion issues.The present disclosure addresses this and the related needs using, interalia, performic acid.

BRIEF SUMMARY OF THE INVENTION

The present invention relates generally to methods for formingperoxyformic acid, comprising contacting formic acid with hydrogenperoxide. In an aspect the contracting of formic acid is with arelatively lower concentration of hydrogen peroxide. In another aspect,the formic acid is formulated with a corrosion inhibitor or otheradditional functional ingredient. In another aspect, the formic acidcontacts a peroxycarboxylic acid composition containing hydrogenperoxide. In an aspect, the contacting step forms a peroxyformic acidwithin a desired time frame and can be treated or contacted undervarious conditions, such as treated with a cation exchange resin such asa strong acid resin column, heated to a desired temperature, or passingthrough a micro reactor under specific conditions.

In one aspect, the present invention is directed to a method for formingperoxyformic acid comprising contacting formic acid with hydrogenperoxide to form a resulting aqueous composition that comprises aperacid that comprises peroxyformic acid, wherein before saidcontacting, the ratio between the concentration of said formic acid(w/v) and the concentration of said hydrogen peroxide (w/v) is about 2or higher, and the ratio between the concentration of said peracid (w/w)and the concentration of hydrogen peroxide (w/w) in said formedresulting aqueous composition reaches about 2 or higher at least within4 hours, or preferably 2 hours of said contacting.

In another aspect, the present invention is directed to peroxyformicacid formed using the above method.

In still another aspect, the present invention is directed to a methodfor treating a target, which method comprises contacting a target withan effective amount of peroxyformic acid formed using the above methodto form a treated target composition, wherein said treated targetcomposition comprises from about 0.1 ppm to about 1,000 ppm of saidperoxyformic acid, and preferably, said contacting lasts for sufficienttime to stabilize or reduce microbial population in and/or on saidtarget or said treated target composition. The present invention furtherrelates to the uses of peroxyformic acid for treating a target, e.g.,target water, including target water used in connection with oil- andgas-field operations. The present invention further relates to methodsfor reducing or removing hydrogen sulfide (H₂S) or iron sulfide in awater source, improving clarity of a water source, or reducing the totaldissolved oxygen or corrosion in a water source, using peroxyformicacid, including peroxyformic acid generated in situ.

While multiple embodiments are disclosed, still other embodiments of thepresent invention will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative embodiments of the invention. Accordingly, the drawings anddetailed description are to be regarded as illustrative in nature andnot restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates formation of peroxyformic acid via addition of formicacid to a peracetic acid/hydrogen peroxide system according toembodiments of the invention.

FIG. 2 illustrates addition of formic acid to a peracid systemcontaining peracetic acid and hydrogen peroxide that results in a shifttowards low hydrogen peroxide concentrations according to embodiments ofthe invention.

FIG. 3 illustrates addition of formic acid to a peracid systemcontaining peroctanoic acid and hydrogen peroxide that results in ashift towards low hydrogen peroxide concentrations according toembodiments of the invention.

FIG. 4 illustrates that soluble mineral acids can be added to accelerateformation of performic acid according to embodiments of the invention.

FIG. 5 illustrates formation of peroxyformic acid via an acid exchangeresin system according to embodiments of the invention.

FIG. 6 illustrates reduction of H₂S in the treated water source usingperoxyformic acid according to embodiments of the invention.

FIG. 7 illustrates reduction of iron sulfide in the treated water sourceusing peroxyformic acid according to embodiments of the invention.

FIG. 8 illustrates improving clarity of the treated water source usingperoxyformic acid as measured by % transmittance according toembodiments of the invention.

FIG. 9 illustrates improving clarity of the treated water source usingperoxyformic acid as shown in the pictures before and after peroxyformicacid treatment according to embodiments of the invention.

FIG. 10 illustrates reduction of the total dissolved oxygen in thetreated water source using peroxyformic acid as measured by O₂production in the treated water source according to embodiments of theinvention.

FIG. 11 illustrates reduction of the total dissolved oxygen in thetreated water source (FIG. 10) using peroxyformic acid as shown by thedarker color that indicates generation of CO₂.

FIG. 12 illustrates reduction of corrosion in the treated water sourceusing peroxyformic acid according to embodiments of the invention.

FIG. 13 illustrates synergy in microbial kill shown as % dead foruntreated, performic acid treated (5 ppm active) and performic acid (5ppm active) in addition to the compounds (50 ppm product) listed inTable 20 according to embodiments of the invention.

FIG. 14 illustrates peroxyformic acid generation at room temperatureusing a stabilizing agent according to embodiments of the invention.

FIG. 15 illustrates the impact of temperature on the kinetics ofperoxyformic acid generation according to embodiments of the invention.

FIG. 16 illustrates peroxyformic acid generation using a catalystaccording to embodiments of the invention.

FIGS. 17-18 illustrate peroxyformic acid generation using a catalyst atdifferent concentrations according to embodiments of the invention.

FIG. 19 illustrates peroxyformic acid generation using a catalyst atvarying temperatures according to embodiments of the invention.

FIG. 20 illustrates the impact of performic acid stability in thepresence of catalysts according to embodiments of the invention.

FIG. 21 shows according to embodiments of the invention that performicacid does not introduce oxygen into the treatment systems.

FIG. 22 illustrates evaluation of oxygen release in evaluated sea watersaccording to embodiments of the invention.

FIG. 23 illustrates corrosion profiles at different ratios of performicacid to peroxide according to embodiments of the invention.

FIG. 24 illustrates corrosion profiles at ratios of performic acid toperoxide of 40:1, 20:1 and 5:1 according to embodiments of theinvention.

FIG. 25 illustrates bubble cell profiles of corrosion inhibitionincluded in formic acid co-formulations according to embodiments of theinvention.

FIG. 26 illustrates corrosion inhibition in PFA treated systemsaccording to embodiments of the invention.

FIG. 27 illustrates the biocidal efficacy of performic acid generatedaccording to embodiments of the invention.

FIG. 28 illustrates the biocidal efficacy of performic acid generatedaccording to embodiments of the invention in produced waters.

FIG. 29 illustrates the biocidal efficacy of performic acid generatedaccording to embodiments of the invention against biofilms.

FIG. 30 illustrates the oxidization of iron sulfide in produced watertreated with performic acid generated according to embodiments of theinvention.

FIG. 31 illustrates the reduction of H₂S in produced water treated withperformic acid generated according to embodiments of the invention.

FIG. 32 illustrates the low temperature disinfectant efficacy ofperformic acid generated according to embodiments of the invention.

Various embodiments of the present invention will be described in detailwith reference to the drawings, wherein like reference numeralsrepresent like parts throughout the several views. Reference to variousembodiments does not limit the scope of the invention. Figuresrepresented herein are not limitations to the various embodimentsaccording to the invention and are presented for exemplary illustrationof the invention.

DETAILED DESCRIPTION OF THE INVENTION

The embodiments of this invention are not limited to particularperoxyformic acid forming compositions, methods for forming peroxyformicacid, the formed peroxyformic acid and methods for using the same, whichcan vary and are understood by skilled artisans. It is further to beunderstood that all terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to belimiting in any manner or scope. For example, all units, prefixes, andsymbols may be denoted in its SI accepted form. Numeric ranges recitedwithin the specification are inclusive of the numbers defining the rangeand include each integer within the defined range.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as is commonly understood by one of ordinary skillin the art to which this invention belongs. All patents, applications,published applications and other publications referred to herein areincorporated by reference in their entireties. If a definition set forthin this section is contrary to or otherwise inconsistent with adefinition set forth in the patents, applications, publishedapplications and other publications that are herein incorporated byreference, the definition set forth in this section prevails over thedefinition that is incorporated herein by reference. So that the presentinvention may be more readily understood, certain terms are firstdefined. Unless defined otherwise, all technical and scientific termsused herein have the same meaning as commonly understood by one ofordinary skill in the art to which embodiments of the invention pertain.Many methods and materials similar, modified, or equivalent to thosedescribed herein can be used in the practice of the embodiments of thepresent invention without undue experimentation, the preferred materialsand methods are described herein. In describing and claiming theembodiments of the present invention, the following terminology will beused in accordance with the definitions set out below.

It should be noted that, as used in this specification and the appendedclaims, the singular forms “a,” “an,” and “the” include plural referentsunless the content clearly dictates otherwise. Thus, for example,reference to a composition containing “a compound” includes acomposition having two or more compounds. It should also be noted thatthe term “or” is generally employed in its sense including “and/or”unless the content clearly dictates otherwise.

As used herein, the term “about” refers to variation in the numericalquantity that can occur, for example, through typical measuring andliquid handling procedures used for making concentrates or use solutionsin the real world; through inadvertent error in these procedures;through differences in the manufacture, source, or purity of theingredients used to make the compositions or carry out the methods; andthe like. The term “about” also encompasses amounts that differ due todifferent equilibrium conditions for a composition resulting from aparticular initial mixture. Whether or not modified by the term “about”,the claims include equivalents to the quantities.

The term “actives” or “percent actives” or “percent by weight actives”or “actives concentration” are used interchangeably herein and refers tothe concentration of those ingredients involved in cleaning expressed asa percentage minus inert ingredients such as water or salts.

As used herein, the phrase “brewery surface” refers to a surface of atool, a machine, equipment, a structure, a building, or the like that isemployed as part of a brewing, making, distilling, preparation,bottling, canning, and storage, etc. of beer, wine, liquor, and spirits.Brewery surface is intended to encompass all surfaces used in brewing(including beer brewing and preparation of liquors and spirits) andwinemaking processes. Examples of brewery surfaces include fermentationvessels, bright beer tanks and lines, mash tuns, bottling equipment,pipes, storage vessels, bottling and canning equipment, etc.

As used herein, the phrases “CIP equipment” and “CIP tank” or anyvariations thereof, refer to tanks, vessels, apparatuses, lines, pumps,and other process equipment used for processing typically liquid productstreams such as beverages, milk, juices, etc. used in CIP cleaningtechniques for removing soils from the internal components. Itencompasses any CIP food processing surfaces and CIP brewery surfaces.

The term “cleaning,” as used herein, means to perform or aid in soilremoval, bleaching, microbial population reduction, or combinationthereof. For the purpose of this patent application, successfulmicrobial reduction is achieved when the microbial populations arereduced by at least about 50%, or by significantly more than is achievedby a wash with water. Larger reductions in microbial population providegreater levels of protection.

As used herein, “consisting essentially of” means that the methods andcompositions may include additional steps, components, ingredients orthe like, but only if the additional steps, components and/oringredients do not materially alter the basic and novel characteristicsof the claimed methods and compositions.

As used herein, the term “disinfectant” refers to an agent that killsall vegetative cells including most recognized pathogenicmicroorganisms, using the procedure described in A.O.A.C. Use DilutionMethods, Official Methods of Analysis of the Association of OfficialAnalytical Chemists, paragraph 955.14 and applicable sections, 15thEdition, 1990 (EPA Guideline 91-2). As used herein, the term “high leveldisinfection” or “high level disinfectant” refers to a compound orcomposition that kills substantially all organisms, except high levelsof bacterial spores, and is effected with a chemical germicide clearedfor marketing as a sterilant by the Food and Drug Administration. Asused herein, the term “intermediate-level disinfection” or “intermediatelevel disinfectant” refers to a compound or composition that killsmycobacteria, most viruses, and bacteria with a chemical germicideregistered as a tuberculocide by the Environmental Protection Agency(EPA). As used herein, the term “low-level disinfection” or “low leveldisinfectant” refers to a compound or composition that kills someviruses and bacteria with a chemical germicide registered as a hospitaldisinfectant by the EPA.

As used herein, the phrase “food processing surface” refers to a surfaceof a tool, a machine, equipment, a structure, a building, or the likethat is employed as part of a food or beverage processing, preparation,or storage activity. Food processing surface is intended to encompassall surfaces used in brewing (including beer brewing and preparation ofliquors and spirits) and winemaking processes (e.g., bright beer tanksand lines, fermentation vessels, mash tuns, bottling equipment, pipes,and storage vessels). Examples of food processing surfaces includesurfaces of food processing or preparation equipment (e.g., boiling,fermenting, slicing, canning, or transport equipment, including flumes),of food processing wares (e.g., utensils, dishware, wash ware, and barglasses), and of floors, walls, or fixtures of structures in which foodprocessing occurs. Food processing surfaces are found and employed infood anti-spoilage air circulation systems, aseptic packagingsanitizing, food refrigeration and cooler cleaners and sanitizers, warewashing sanitizing, blancher cleaning and sanitizing, food packagingmaterials, cutting board additives, third-sink sanitizing, beveragechillers and warmers, meat chilling or scalding waters, autodishsanitizers, sanitizing gels, cooling towers, food processingantimicrobial garment sprays, and non-to-low-aqueous food preparationlubricants, oils, and rinse additives.

As used herein, the phrase “food product” includes any food substancethat might require treatment with an antimicrobial agent or compositionand that is edible with or without further preparation. Food productsinclude meat (e.g. red meat and pork), seafood, poultry, produce (e.g.,fruits and vegetables), eggs, living eggs, egg products, ready to eatfood, wheat, seeds, roots, tubers, leafs, stems, corns, flowers,sprouts, seasonings, or a combination thereof. The term “produce” refersto food products such as fruits and vegetables and plants orplant-derived materials that are typically sold uncooked and, often,unpackaged, and that can sometimes be eaten raw.

As used herein, the term “free,” “no,” “substantially no” or“substantially free” refers to a composition, mixture, or ingredientthat does not contain a particular compound or to which a particularcompound or a particular compound-containing compound has not beenadded. In some embodiments, the reduction and/or elimination of hydrogenperoxide according to embodiments provide hydrogen peroxide-free orsubstantially-free compositions. Should the particular compound bepresent through contamination and/or use in a minimal amount of acomposition, mixture, or ingredients, the amount of the compound shallbe less than about 3 wt-%. More preferably, the amount of the compoundis less than 2 wt-%, less than 1 wt-%, and most preferably the amount ofthe compound is less than 0.5 wt-%.

The term “hard surface” refers to a solid, substantially non-flexiblesurface such as a counter top, tile, floor, wall, panel, window,plumbing fixture, kitchen and bathroom furniture, appliance, engine,circuit board, and dish. Hard surfaces may include for example, healthcare surfaces and food processing surfaces.

As used herein, the term “microorganism” refers to any noncellular orunicellular (including colonial) organism. Microorganisms include allprokaryotes. Microorganisms include bacteria (including cyanobacteria),spores, lichens, fungi, protozoa, virinos, viroids, viruses, phages, andsome algae. As used herein, the term “microbe” is synonymous withmicroorganism.

As used herein, the terms “mixed” or “mixture” when used relating to“percarboxylic acid composition,” “percarboxylic acids,”“peroxycarboxylic acid composition” or “peroxycarboxylic acids” refer toa composition or mixture including more than one percarboxylic acid orperoxycarboxylic acid.

As used herein, the term “sanitizer” refers to an agent that reduces thenumber of bacterial contaminants to safe levels as judged by publichealth requirements. In an embodiment, sanitizers for use in thisinvention will provide at least a 99.999% reduction (5-log orderreduction). These reductions can be evaluated using a procedure set outin Germicidal and Detergent Sanitizing Action of Disinfectants, OfficialMethods of Analysis of the Association of Official Analytical Chemists,paragraph 960.09 and applicable sections, 15th Edition, 1990 (EPAGuideline 91-2). According to this reference a sanitizer should providea 99.999% reduction (5-log order reduction) within 30 seconds at roomtemperature, 25±2° C., against several test organisms.

Differentiation of antimicrobial “-cidal” or “-static” activity, thedefinitions which describe the degree of efficacy, and the officiallaboratory protocols for measuring this efficacy are considerations forunderstanding the relevance of antimicrobial agents and compositions.Antimicrobial compositions can affect two kinds of microbial celldamage. The first is a lethal, irreversible action resulting in completemicrobial cell destruction or incapacitation. The second type of celldamage is reversible, such that if the organism is rendered free of theagent, it can again multiply. The former is termed microbiocidal and thelater, microbistatic. A sanitizer and a disinfectant are, by definition,agents which provide antimicrobial or microbiocidal activity. Incontrast, a preservative is generally described as an inhibitor ormicrobistatic composition.

As used herein, the term “water” for treatment according to theinvention includes a variety of sources, such as freshwater, pond water,sea water, salt water or brine source, brackish water, recycled water,or the like. Waters are also understood to optionally include both freshand recycled water sources (e.g. “produced waters”), as well as anycombination of waters for treatment according to the invention. In someembodiments, produced water (or reuse water) refers to a mixture ofwater that comprises both water recycled from previous or concurrentoil- and gas-field operations, e.g., fracking, and water that has notbeen used in oil- and gas-field operations, e.g., fresh water, pondwater, sea water, etc.

As used herein, “weight percent,” “wt-%,” “percent by weight,” “% byweight,” and variations thereof refer to the concentration of asubstance as the weight of that substance divided by the total weight ofthe composition and multiplied by 100. It is understood that, as usedhere, “percent,” “%,” and the like are intended to be synonymous with“weight percent,” “wt-%,” etc.

It is understood that aspects and embodiments of the invention describedherein include “consisting” and/or “consisting essentially of” aspectsand embodiments.

Throughout this disclosure, various aspects of this invention arepresented in a range format. It should be understood that thedescription in range format is merely for convenience and brevity andshould not be construed as an inflexible limitation on the scope of theinvention. Accordingly, the description of a range should be consideredto have specifically disclosed all the possible sub-ranges as well asindividual numerical values within that range. For example, descriptionof a range such as from 1 to 6 should be considered to have specificallydisclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numberswithin that range, for example, 1, 2, 3, 4, 5, and 6. This appliesregardless of the breadth of the range.

Methods for Forming Peroxyformic Acid

In one aspect, the present invention is directed to a method for formingperoxyformic acid comprising contacting formic acid with hydrogenperoxide to form a resulting aqueous composition that comprises aperacid that comprises peroxyformic acid, wherein before saidcontacting, the ratio between the concentration of said formic acid(w/v) and the concentration of said hydrogen peroxide (w/v) is about 2or higher, and the ratio between the concentration of said peracid (w/w)and the concentration of hydrogen peroxide (w/w) in said formedresulting aqueous composition reaches about 2 or higher at least within4 hours, or preferably 2 hours of said contacting.

The formic acid used in the present methods can be provided in anysuitable way.

In some embodiments, before the contacting step, the formic acid can beprovided in a composition that comprises formic acid, e.g., an aqueoussolution that comprises formic acid. In other embodiments, before thecontacting step, the formic acid can be provided in a composition thatcomprises a substance that generates formic acid upon contact with anaqueous composition. Any suitable substance that generates formic acidcan be used in the present methods. The substance can be a salt offormate, e.g., a sodium or ammonium salt of formate, or an ester offormate. Exemplary esters of formate include glycerol formates,pentaerythritol formates, mannitol formates, propylene glycol formates,sorbitol formates and sugar formates. Exemplary sugar formates includesucrose formates, dextrin formates, maltodextrin formates, and starchformates. In some embodiments the formates may be provided in a solidcomposition, such as a starch formate.

The hydrogen peroxide used in the present methods can be provided in anysuitable way. In some embodiments, before the contacting step, thehydrogen peroxide can be provided in a composition that compriseshydrogen peroxide, e.g., an aqueous solution that comprises hydrogenperoxide. In other embodiments, before the contacting step, the hydrogenperoxide can be provided in a composition that comprises a substancethat generates hydrogen peroxide upon contact with an aqueouscomposition. Any suitable substance that generates hydrogen peroxide canbe sued in the present methods. The substance can comprise a precursorof hydrogen peroxide. Any suitable precursor of hydrogen peroxide can beused in the present methods. For example, the precursor of hydrogenperoxide can be sodium percarbonate, sodium perborate, urea hydrogenperoxide, or PVP-hydrogen peroxide.

In some embodiments, formic acid provided in a first aqueous compositionis contacted with hydrogen peroxide provided in a second aqueouscomposition to form peroxyformic acid in the resulting aqueouscomposition. In other embodiments, formic acid provided in a firstaqueous composition is contacted with a substance that generateshydrogen peroxide upon contact with an aqueous composition provided in asecond solid composition to form peroxyformic acid in the resultingaqueous composition. In still other embodiments, a substance thatgenerates formic acid upon contact with an aqueous composition providedin a first solid composition is contacted with hydrogen peroxideprovided in a second aqueous composition to form peroxyformic acid inthe resulting aqueous composition. In yet other embodiments, a substancethat generates formic acid upon contact with an aqueous compositionprovided in a first solid composition and a substance that generateshydrogen peroxide upon contact with an aqueous composition provided in asecond solid composition are contacted with a third aqueous compositionto form peroxyformic acid in the resulting aqueous composition. In yetother embodiments, a substance that generates formic acid upon contactwith an aqueous composition and a substance that generates hydrogenperoxide upon contact with an aqueous composition are provided in afirst solid composition, and the first solid composition is contactedwith a second aqueous composition to form peroxyformic acid in theresulting aqueous composition.

The resulting aqueous composition that comprises a peracid thatcomprises peroxyformic acid can be any suitable types of aqueouscompositions. For example, the resulting aqueous composition can be anaqueous solution. In another example, the resulting aqueous compositioncan be an aqueous suspension.

Before the contacting step, the ratio between the concentration of theformic acid (w/v) and the concentration of the hydrogen peroxide (w/v)can be in any suitable range. In some embodiments, before thecontacting, the ratio between the concentration of the formic acid (w/v)and the concentration of the hydrogen peroxide (w/v) can be from about 2to about 100, e.g., about 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10,10-15, 15-20, 20-25, 25-30, 30-35, 35-40, 40-45 or 45-50 or greater fromabout 50-100.

The ratio between the concentration of the peracid (w/w) and theconcentration of hydrogen peroxide (w/w) in the formed aqueouscomposition can reach any suitable range. In some embodiments, the ratiobetween the concentration of the peracid (w/w) and the concentration ofhydrogen peroxide (w/w) in the formed aqueous composition can reach,within about 4 hours, or preferably 2 hours of the contacting, fromabout 2 to about 1,500, e.g., about 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9,9-10, 10-15, 15-20, 20-25, 25-30, 30-35, 35-40, 40-45, 45-50, 50-60,60-70, 70-80, 80-90, 90-100, 100-200, 200-300, 300-400, 400-500,500-600, 600-700, 700-800, 800-900, 900-1,000, 1,000-1,100, 1,100-1,200,1,200-1,300, 1,300-1,400, or 1,400-1,500. In other embodiments, theratio between the concentration of the peracid (w/w) and theconcentration of hydrogen peroxide (w/w) in the formed aqueouscomposition reaches at least about 10 within about 30 minutes of thecontacting, preferably at least about 10-40 within about 30 minutes ofthe contacting.

The formed aqueous composition can comprise any suitable concentrationof hydrogen peroxide. In some embodiments, the formed aqueouscomposition can comprise about 5% (w/w) or less hydrogen peroxide, e.g.,about 5% (w/w), 4.5% (w/w), 4% (w/w), 3.5% (w/w), 3% (w/w), 2.5% (w/w),2% (w/w), 1.5% (w/w), 1% (w/w), 0.9% (w/w), 0.8% (w/w), 0.7% (w/w), 0.6%(w/w), 0.5% (w/w), 0.4% (w/w), 0.3% (w/w), 0.2% (w/w), 0.1% (w/w), 0.05%(w/w), 0.01% (w/w), 0.005% (w/w), or 0.001% (w/w) of hydrogen peroxide.In other embodiments, the formed aqueous composition reaches about 2%(w/w) or less hydrogen peroxide within at least about 4 hours, orpreferably 2 hours of the contacting. In still other embodiments, theformed aqueous composition reaches about 1% (w/w) or less hydrogenperoxide within at least about 1 hour of the contacting. In yet otherembodiments, the formed aqueous composition reaches about 0% (w/w) toabout 0.001% (w/w) hydrogen peroxide and maintains about 0% (w/w) toabout 0.001% (w/w) hydrogen peroxide for at least 1 hour.

The formic acid and the hydrogen peroxide can be contacted in theabsence of a C₂-C₂₂ carboxylic acid and/or a C₂-C₂₂ percarboxylic acidand the peracid in the formed aqueous composition comprises peroxyformicacid only.

The formic acid and hydrogen peroxide can be contacted in the presenceof a C₂-C₂₂ carboxylic acid and the peracid in the formed aqueouscomposition comprises peroxyformic acid and the C₂-C₂₂ percarboxylicacid. Any suitable C₂-C₂₂ carboxylic acid can be used in the presentmethods. In some embodiments, the C₂-C₂₂ carboxylic acid is acetic acid,octanoic acid and/or sulfonated oleic acid, and the peracid in theformed aqueous composition comprises peroxyformic acid and one or moreof peroxyacetic acid, peroxyoctanoic acid and peroxysulfonated oleicacid.

The formic acid and the hydrogen peroxide can be contacted in thepresence of a C₂-C₂₂ percarboxylic acid and the peracid in the formedaqueous composition comprises peroxyformic acid and the C₂-C₂₂percarboxylic acid. Any suitable C₂-C₂₂ percarboxylic acid can be usedin the present methods. In some embodiments, the C₂-C₂₂ percarboxylicacid can be peroxyacetic acid, peroxyoctanoic acid and/orperoxysulfonated oleic acid.

The present methods can be conducted at any suitable temperature. Insome embodiments, the present methods can be conducted at a temperatureranging from about −2° C. to about 70° C., about 10° C. to about 70° C.,e.g., about 10° C.-15° C., 15° C.-20° C., 20° C.-25° C., 25° C.-30° C.,30° C.-35° C., 35° C.-40° C., 40° C.-45° C., 45° C.-50° C., 50° C.-55°C., 55° C.-60° C., 60° C.-65° C., or 65° C.-70° C. In other embodiments,the present methods can be conducted under ambient conditions. In stillother embodiments, the present methods can be conducted under heating,e.g., at a temperature ranging from about 30° C.-35° C., 35° C.-40° C.,40° C.-45° C., 45° C.-50° C., 50° C.-55° C., 55° C.-60° C., 60° C.-65°C., or 65° C.-70° C.

The present methods can be conducted in the presence of a catalyst. Anysuitable catalyst can be used in the present methods. In someembodiments, the catalyst can be a mineral acid, e.g., sulfuric acid,methanesulfonic acid, nitric acid, phosphoric acid, pyrophosphoric acid,polyphosphoric acid or phosphonic acid.

The present methods can be conducted in the presence of a cation acidexchange resin system. Any suitable cation acid exchange resin systemcan be used in the present methods. In some embodiments, the cation acidexchange resin system is a strong cation acid exchange resin system. Inother embodiments, the acid exchange resin system is sulfonic acidexchange resin, e.g., commercially-available as Dowex M-31 or Nafion.

The formic acid provided in a first aqueous composition can be contactedwith the hydrogen peroxide provided in a second aqueous composition thatalso comprises peroxyacetic acid to form a resulting aqueous compositionthat comprises a total peracid that comprises peroxyformic acid andperoxyacetic acid. Before the contacting step, the ratio between theconcentration of the formic acid (w/v) and the concentration of thehydrogen peroxide (w/v) can be at any suitable range. The ratio betweenthe concentration of total peracid (w/w) and the concentration ofhydrogen peroxide (w/w) in the resulting aqueous composition can alsoreach any suitable range. In some embodiments, before the contacting,the ratio between the concentration of the formic acid (w/v) and theconcentration of the hydrogen peroxide (w/v) can be about 5 or higherand the ratio between the concentration of total peracid (w/w) and theconcentration of hydrogen peroxide (w/w) in the resulting aqueouscomposition reaches at least about 5 within about 2 minutes of thecontacting. In other embodiments, the ratio between the concentration oftotal peracid (w/w) and the concentration of hydrogen peroxide (w/w) inthe resulting aqueous composition can reach at least about 10 withinabout 20 minutes of the contacting. In still other embodiments, theratio between the concentration of total peracid (w/w) and theconcentration of hydrogen peroxide (w/w) in the resulting aqueouscomposition can reach at least about 50 within about 30 hours of thecontacting. In yet other embodiments, before the contacting, the ratiobetween the concentration of the formic acid (w/v) and the concentrationof the hydrogen peroxide (w/v) can be about 20 or higher and the ratiobetween the concentration of total peracid (w/w) and the concentrationof hydrogen peroxide (w/w) in the resulting aqueous composition canreach at least about 10 within at least about 1 minute of thecontacting. The concentration of hydrogen peroxide (w/w) in theresulting aqueous composition can reach any suitable concentration. Insome embodiments, the concentration of hydrogen peroxide (w/w) in theresulting aqueous composition can reach about 0% (w/w) to about 0.001%(w/w) hydrogen peroxide within at least about 4 hours, or preferably 2hours of the contacting. In other embodiments, the concentration ofhydrogen peroxide (w/w) in the resulting aqueous composition can remainat about 0% (w/w) to about 0.001% (w/w) for least 1 hour.

The formic acid provided in a first aqueous composition can be contactedwith the hydrogen peroxide provided in a second aqueous composition thatalso comprises peroxyoctanoic acid to form a resulting aqueouscomposition that comprises a total peracid that comprises peroxyformicacid and peroxyoctanoic acid. Before the contacting step, the ratiobetween the concentration of the formic acid (w/v) and the concentrationof the hydrogen peroxide (w/v) can be at any suitable range. The ratiobetween the concentration of total peracid (w/w) and the concentrationof hydrogen peroxide (w/w) in the resulting aqueous composition can alsoreach any suitable range. In some embodiments, the ratio between theconcentration of the formic acid (w/v) and the concentration of thehydrogen peroxide (w/v) can be about 5 or higher and the ratio betweenthe concentration of total peracid (w/w) and the concentration ofhydrogen peroxide (w/w) in the resulting aqueous composition can reachat least about 5 within at least about 30 minutes of the contacting.

In some embodiments, a salt of formate or an ester of formate in a firstcomposition, e.g., a first solid or liquid composition, can be contactedwith hydrogen peroxide and a C₂-C₂₂ percarboxylic acid provided in asecond aqueous composition to form a resulting aqueous composition thatcomprises peroxyformic acid and the C₂-C₂₂ percarboxylic acid. Beforethe contacting, the second aqueous composition can comprise any suitableconcentration of the C₂-C₂₂ percarboxylic acid, and the salt of formateor ester of formate can be added to the second aqueous composition sothat the aqueous composition comprises any suitable concentration of thesalt of formate or ester of formate. The ratio between the concentrationof total peracid (w/w) and the concentration of hydrogen peroxide (w/w)in the resulting aqueous composition can reach any suitable range. Forexample, before the contacting, the second aqueous composition comprisesfrom about 1 (w/v) to about 40 (w/v) of the C₂-C₂₂ percarboxylic acid,the salt of formate or ester of formate is added to the second aqueouscomposition so that the aqueous composition comprises from about 5 (w/v)to about 30 (w/v) of the salt of formate or ester of formate, and theratio between the concentration of total peracid (w/w) and theconcentration of hydrogen peroxide (w/w) in the resulting aqueouscomposition reaches at least about 2 within at least about 3 hours ofthe contacting. In another example, the concentration of hydrogenperoxide (w/w) in the resulting aqueous composition can reach about0.001% (w/w) to about 10% (w/w) within at least about 3 hours of thecontacting.

The resulting aqueous composition can comprise a stabilizing agent forthe peracid. Any suitable stabilizing agents can be used in the presentmethods. Exemplary stabilizing agents include a phosphonate salt(s)and/or a heterocyclic dicarboxylic acid, e.g., dipicolinic acid.

The present methods can further comprise a step of reducing theconcentration of the hydrogen peroxide in the resulting aqueouscomposition. The concentration of the hydrogen peroxide in the resultingaqueous composition can be reduced using any suitable methods. Forexample, the concentration of the hydrogen peroxide in the resultingaqueous composition can be reduced using a catalase or a peroxidase.

The resulting aqueous composition can comprise any suitableconcentration of peroxyformic acid. In some embodiments, the resultingaqueous composition comprises from about 0.001% (w/w) to about 20% (w/w)peroxyformic acid, e.g., about 0.001%-0.005% (w/w), 0.005%-0.01% (w/w),0.01%-0.05% (w/w), 0.05%-0.1% (w/w), 0.1%-0.5% (w/w), 0.5%-1% (w/w),1%-2% (w/w), 2%-3% (w/w), 3%-4% (w/w), 4%-5% (w/w), 5%-6% (w/w), 6%-7%(w/w), 7%-8% (w/w), 8%-9% (w/w), 9%-10% (w/w), 10%-11% (w/w), 11%-12%(w/w) 12%-13% (w/w) 13%-14% (w/w) 14%-15% (w/w) 15%-16% (w/w) 16%-17%(w/w) 17%-18% (w/w) 18%-19% (w/w) 19%-20% (w/w) peroxyformic acid.

The present methods can further comprise adding a corrosion inhibitor sothat the formed resulting aqueous composition comprises the corrosioninhibitor. Any suitable corrosion inhibitor can be used. In someembodiments, the corrosion inhibitor can be a phosphate ester, aderivative of the phosphate ester, a diacid, a derivative of the diacid,a quat amine, a derivative of the quat amine, an imidazoline, aderivative of the imidazoline, an alkyl pyridine, a derivative of thealkyl pyridine, a phosphonium salt, a derivative of the phosphoniumsalt, or a combination thereof.

The corrosion inhibitor can be used at any suitable concentration. Insome embodiments, the formed resulting aqueous composition can comprisefrom about 0.1 ppm to about 50,000 ppm of the corrosion inhibitor, e.g.,about 1-10 ppm, 10-20 ppm, 20-30 ppm, 30-40 ppm, 40-50 ppm, 50-60 ppm,60-70 ppm, 70-80 ppm, 80-90 ppm, 90-100 ppm, 100-150 ppm, 150-200 ppm,200-250 ppm, 250-300 ppm, 300-350 ppm, 350-400 ppm, 400-450 ppm, 450-500ppm, 500-550 ppm, 550-600 ppm, 600-650 ppm, 650-700 ppm, 700-750 ppm,750-800 ppm, 800-850 ppm, 850-900 ppm, 900-950 ppm, 950-1,000 ppm,1,000-1,500 ppm, 1,500-2,000 ppm, 2,000-2,500 ppm, 2,500-3,000 ppm,3,000-3,500 ppm, 3,500-4,000 ppm, 4,000-4,500 ppm, or 4,500-5,000 ppm,5,000-5,500 ppm, 5,500-6,000 ppm, 6,000-6,500 ppm, 6,500-7,000 ppm,7,000-7,500 ppm, 7,500-8,000, 8,000-8,500 ppm, 8,500-9,000 ppm,9,000-9,500 ppm, or 9,500-10,000 ppm. In other embodiments, the ratiobetween the concentration of the peroxyformic acid (w/v) and theconcentration of the corrosion inhibitor (w/v) in the formed resultingaqueous composition can be from about 0.01 to about 100, e.g., about0.01-0.05, 0.05-0.1, 0.1-0.5, 0.5-1, 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8,8-9, 9-10, 10-15, 15-20, 20-25, 25-30, 30-35, 35-40, 40-45, 45-50,50-60, 60-70, 70-80, 80-90, 90-100.

The corrosion inhibitor can be added at any suitable time. In someembodiments, the corrosion inhibitor can be added before the formic acidis contacted with the hydrogen peroxide. In other embodiments, thecorrosion inhibitor can be added concurrently when the formic acid iscontacted with the hydrogen peroxide. In still other embodiments, thecorrosion inhibitor can be added after the formic acid is contacted withthe hydrogen peroxide.

The present methods can be used to generate peroxyformic acid in anysuitable manner or at any suitable location. In some embodiments, thepresent methods can be used to generate peroxyformic acid in situ forthe application of the formed peroxyformic acid.

In another aspect, the present invention is directed to peroxyformicacid formed using the present methods, e.g., peroxyformic acid formed insitu for the application of the formed peroxyformic acid, and aperoxyformic acid formed composition formed using the present methods inthe presence of a corrosion inhibitor.

The peroxyformic acid formed using the present methods (presentcomposition) can further comprise other percarboxylic acids. Variousembodiments of the invention referring to peroxyformic acid compositionsand/or peroxyformic acid solutions are further understood to optionallycomprise additional percarboxylic acids. As used herein, the term“peracid” may also be referred to as a “percarboxylic acid” or“peroxyacid.” Sulfoperoxycarboxylic acids, sulfonated peracids andsulfonated peroxycarboxylic acids are also included within the term“peracid” as used herein. The terms “sulfoperoxycarboxylic acid,”“sulfonated peracid,” or “sulfonated peroxycarboxylic acid” refers tothe peroxycarboxylic acid form of a sulfonated carboxylic acid asdisclosed in U.S. Patent Publication Nos. 2010/0021557, 2010/0048730 and2012/0052134 which are incorporated herein by reference in theirentireties. A peracid refers to an acid having the hydrogen of thehydroxyl group in carboxylic acid replaced by a hydroxy group. Oxidizingperacids may also be referred to herein as peroxycarboxylic acids.

In some embodiments, peroxyformic acid with other peroxycarboxylic acidscan be generated by mixing an ester of a polyhydric alcohol with acomposition comprising peroxycaboxylic acid(s) and hydrogen peroxide toform a composition that comprises both peroxyformic acid and otherperoxycarboxylic acids. Examples of commercially-available compositionscomprising both peroxycarboxylic acid and hydrogen peroxide includeperoxyacetic acid compositions, peroxyoctanoic acid compositions, etc.all commercially available from Ecolab Inc. In use, an ester of apolyhydric alcohol can be contacted, e.g., mixed, with such peroxyaceticacid compositions, peroxyoctanoic acid compositions, etc., to form acomposition that comprises both peroxyformic acid and other desiredperoxycarboxylic acids.

A peracid includes any compound of the formula R—(COOOH)_(n) in which Rcan be hydrogen, alkyl, alkenyl, alkyne, acrylic, alicyclic group, aryl,heteroaryl, or heterocyclic group, and n is 1, 2, or 3, and named byprefixing the parent acid with peroxy. Preferably R includes hydrogen,alkyl, or alkenyl. The terms “alkyl,” “alkenyl,” “alkyne,” “acrylic,”“alicyclic group,” “aryl,” “heteroaryl,” and “heterocyclic group” are asdefined herein.

As used herein, the term “alkyl” includes a straight or branchedsaturated aliphatic hydrocarbon chain having from 1 to 22 carbon atoms,such as, for example, methyl, ethyl, propyl, isopropyl (1-methylethyl),butyl, tert-butyl (1,1-dimethylethyl), and the like. The term “alkyl” or“alkyl groups” also refers to saturated hydrocarbons having one or morecarbon atoms, including straight-chain alkyl groups (e.g., methyl,ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, etc.),cyclic alkyl groups (or “cycloalkyl” or “alicyclic” or “carbocyclic”groups) (e.g., cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl,cyclooctyl, etc.), branched-chain alkyl groups (e.g., isopropyl,tert-butyl, sec-butyl, isobutyl, etc.), and alkyl-substituted alkylgroups (e.g., alkyl-substituted cycloalkyl groups andcycloalkyl-substituted alkyl groups).

Unless otherwise specified, the term “alkyl” includes both“unsubstituted alkyls” and “substituted alkyls.” As used herein, theterm “substituted alkyls” refers to alkyl groups having substituentsreplacing one or more hydrogens on one or more carbons of thehydrocarbon backbone. Such substituents may include, for example,alkenyl, alkynyl, halogeno, hydroxyl, alkylcarbonyloxy, arylcarbonyloxy,alkoxycarbonyloxy, aryloxy, aryloxycarbonyloxy, carboxylate,alkylcarbonyl, arylcarbonyl, alkoxycarbonyl, aminocarbonyl,alkylaminocarbonyl, dialkylaminocarbonyl, alkylthiocarbonyl, alkoxyl,phosphate, phosphonato, phosphinato, cyano, amino (including alkylamino, dialkylamino, arylamino, diarylamino, and alkylarylamino),acylamino (including alkylcarbonylamino, arylcarbonylamino, carbamoyland ureido), imino, sulfhydryl, alkylthio, arylthio, thiocarboxylate,sulfates, alkylsulfinyl, sulfonates, sulfamoyl, sulfonamido, nitro,trifluoromethyl, cyano, azido, heterocyclic, alkylaryl, or aromatic(including heteroaromatic) groups.

The term “alkenyl” includes an unsaturated aliphatic hydrocarbon chainhaving from 2 to 12 carbon atoms, such as, for example, ethenyl,1-propenyl, 2-propenyl, 1-butenyl, 2-methyl-1-propenyl, and the like.The alkyl or alkenyl can be terminally substituted with a heteroatom,such as, for example, a nitrogen, sulfur, or oxygen atom, forming anaminoalkyl, oxyalkyl, or thioalkyl, for example, aminomethyl, thioethyl,oxypropyl, and the like. Similarly, the above alkyl or alkenyl can beinterrupted in the chain by a heteroatom forming an alkylaminoalkyl,alkylthioalkyl, or alkoxyalkyl, for example, methylaminoethyl,ethylthiopropyl, methoxymethyl, and the like.

Further, as used herein the term “alicyclic” includes any cyclichydrocarbyl containing from 3 to 8 carbon atoms. Examples of suitablealicyclic groups include cyclopropanyl, cyclobutanyl, cyclopentanyl,etc. The term “heterocyclic” includes any closed ring structuresanalogous to carbocyclic groups in which one or more of the carbon atomsin the ring is an element other than carbon (heteroatom), for example, anitrogen, sulfur, or oxygen atom. Heterocyclic groups may be saturatedor unsaturated. Examples of suitable heterocyclic groups include forexample, aziridine, ethylene oxide (epoxides, oxiranes), thiirane(episulfides), dioxirane, azetidine, oxetane, thietane, dioxetane,dithietane, dithiete, azolidine, pyrrolidine, pyrroline, oxolane,dihydrofuran, and furan. Additional examples of suitable heterocyclicgroups include groups derived from tetrahydrofurans, furans, thiophenes,pyrrolidines, piperidines, pyridines, pyrrols, picoline, coumaline, etc.

In some embodiments, alkyl, alkenyl, alicyclic groups, and heterocyclicgroups can be unsubstituted or substituted by, for example, aryl,heteroaryl, C₁₋₄ alkyl, C₁₋₄ alkenyl, C₁₋₄ alkoxy, amino, carboxy, halo,nitro, cyano, —SO₃H, phosphono, or hydroxy. When alkyl, alkenyl,alicyclic group, or heterocyclic group is substituted, preferably thesubstitution is C₁₋₄ alkyl, halo, nitro, amido, hydroxy, carboxy,sulpho, or phosphono. In one embodiment, R includes alkyl substitutedwith hydroxy. The term “aryl” includes aromatic hydrocarbyl, includingfused aromatic rings, such as, for example, phenyl and naphthyl. Theterm “heteroaryl” includes heterocyclic aromatic derivatives having atleast one heteroatom such as, for example, nitrogen, oxygen, phosphorus,or sulfur, and includes, for example, furyl, pyrrolyl, thienyl,oxazolyl, pyridyl, imidazolyl, thiazolyl, isoxazolyl, pyrazolyl,isothiazolyl, etc. The term “heteroaryl” also includes fused rings inwhich at least one ring is aromatic, such as, for example, indolyl,purinyl, benzofuryl, etc.

In some embodiments, aryl and heteroaryl groups can be unsubstituted orsubstituted on the ring by, for example, aryl, heteroaryl, alkyl,alkenyl, alkoxy, amino, carboxy, halo, nitro, cyano, —SO₃H, phosphono,or hydroxy. When aryl, aralkyl, or heteroaryl is substituted, preferablythe substitution is C₁₋₄ alkyl, halo, nitro, amido, hydroxy, carboxy,sulpho, or phosphono. In one embodiment, R includes aryl substitutedwith C₁₋₄ alkyl.

Peracids suitable for use include any peroxycarboxylic acids, includingvarying lengths of peroxycarboxylic and percarboxylic acids (e.g. C1-22)that can be prepared from the acid-catalyzed equilibrium reactionbetween a carboxylic acid described above and hydrogen peroxide.Additional suitable peracids include those prepared from the reaction ofan ester of a polyhydric alcohol and formic acid with hydrogen peroxide.A peroxycarboxylic acid can also be prepared by the auto-oxidation ofaldehydes or by the reaction of hydrogen peroxide with an acid chloride,acid hydride, carboxylic acid anhydride, or sodium alcoholate.Alternatively, peracids can be prepared through non-equilibriumreactions, which may be generated for use in situ, such as the methodsdisclosed in U.S. Pat. Nos. 8,846,107 and 8,877,254 each titled “In SituGeneration of Peroxycarboxylic Acids at Alkaline pH, and Methods of UseThereof,” which are incorporated herein by reference. Preferably acomposition of the invention includes peroxyformic acid, peroxyaceticacid, peroxyoctanoic acid, peroxypropionic acid, peroxylactic acid,peroxyheptanoic acid, peroxyoctanoic acid and/or peroxynonanoic acid.

In some embodiments, a peroxycarboxylic acid includes at least onewater-soluble peroxycarboxylic acid in which R includes alkyl of 1-22carbon atoms. For example, in one embodiment, a peroxycarboxylic acidincludes peroxyformic acid and/or peroxyacetic acid. In anotherembodiment, a peroxycarboxylic acid has R that is an alkyl of 1-22carbon atoms substituted with hydroxy. Methods of preparing peroxyaceticacid are known to those of skill in the art including those disclosed inU.S. Pat. No. 2,833,813, which is herein incorporated herein byreference.

In another embodiment, a sulfoperoxycarboxylic acid has the followingformula:

wherein R₁ is hydrogen, or a substituted or unsubstituted alkyl group;R₂ is a substituted or unsubstituted alkylene group; X is hydrogen, acationic group, or an ester forming moiety; or salts or esters thereof.In additional embodiments, a sulfoperoxycarboxylic acid is combined witha single or mixed peroxycarboxylic acid composition, such as asulfoperoxycarboxylic acid with peroxyacetic acid and peroxyoctanoicacid (PSOA/POOA/POAA).

In other embodiments, a mixed peracid is employed, such as aperoxycarboxylic acid including at least one peroxycarboxylic acid oflimited water solubility in which R includes alkyl of 5-22 carbon atomsand at least one water-soluble peroxycarboxylic acid in which R includesalkyl of 1-4 carbon atoms. For example, in one embodiment, aperoxycarboxylic acid includes peroxyacetic acid and at least one otherperoxycarboxylic acid such as those named above. Preferably acomposition of the invention includes peroxyformic acid, peroxyaceticacid and/or peroxyoctanoic acid. Other combinations of mixed peracidsare well suited for use in the current invention.

In another embodiment, a mixture of peroxyformic acid, and peraceticacid or peroctanoic acid is used to treat a water source, such asdisclosed in U.S. Pat. No. 5,314,687 which is herein incorporated byreference in its entirety. In an aspect, the peracid mixture is ahydrophilic peroxyformic acid or peracetic acid and a hydrophobicperoctanoic acid, providing antimicrobial synergy. In an aspect, thesynergy of a mixed peracid system allows the use of lower dosages of theperacids.

In another embodiment, a tertiary peracid mixture composition, such asperoxysulfonated oleic acid, peroxyformic acid and peroctanoic acid areused to treat a water source, such as disclosed in U.S. PatentPublication No. 2010/00021557 which is incorporated herein by referencein its entirety. A combination of the three peracids providessignificant antimicrobial synergy providing an efficient antimicrobialcomposition for the water treatment methods according to the invention.In addition, it is thought the high acidity built in the compositionassists in removing chemical contaminants from the water (e.g. sulfiteand sulfide species).

Advantageously, a combination of peroxycarboxylic acids provides acomposition with desirable antimicrobial activity in the presence ofhigh organic soil loads. The mixed peroxycarboxylic acid compositionsoften provide synergistic micro efficacy. Accordingly, compositions ofthe invention can include a peroxycarboxylic acid, or mixtures thereof.

Various commercial formulations of peracids are available, including forexample, peracetic acid (15%) available from Ecolab Inc., St. Paul Minn.Most commercial peracid solutions state a specific percarboxylic acidconcentration without reference to the other chemical components in ause solution. However, it should be understood that commercial products,such as peracetic acid, will also contain the corresponding carboxylicacid (e.g. acetic acid), hydrogen peroxide and water.

Any suitable C₁-C₂₂ percarboxylic acid can be used in the presentcompositions. In some embodiments, the C₁-C₂₂ percarboxylic acid is aC₂-C₂₀ percarboxylic acid. In other embodiments, the C₁-C₂₂percarboxylic is a C₁, C₂, C₃, C₄, C₅, C₆, C₇, C₈, C₉, C₁₀, C₁₁, C₁₂,C₁₃, C₁₄, C₁₅, C₁₆, C₁₇, C₁₈, C₁₉, C₂₀, C₂₁, or C₂₂ carboxylic acid. Instill other embodiments, the C₁-C₂₂ percarboxylic acid comprisesperoxyformic acid, peroxyacetic acid, peroxyoctanoic acid and/orperoxysulfonated oleic acid.

The C₁-C₂₂ percarboxylic acid can be used at any suitable concentration.In some embodiments, the C₁-C₂₂ percarboxylic acid has a concentrationfrom about 1 wt-% to about 40 wt-%. In other embodiments, the C₁-C₂₂percarboxylic acid has a concentration from about 1 wt-% to about 20wt-%. In still other embodiments, the C₁-C₂₂ percarboxylic acid has aconcentration at about 1 wt-%, 2 wt-%, 3 wt-%, 4 wt-%, 5 wt-%, 6 wt-%, 7wt-%, 8 wt-%, 9 wt-%, 10 wt-%, 11 wt-%, 12 wt-%, 13 wt-%, 14 wt-%, 15wt-%, 16 wt-%, 17 wt-%, 18 wt-%, 19 wt-%, 20 wt-%, 25 wt-%, 30 wt-%, 35wt-%, or 40 wt-%. In yet other embodiments, the C₁-C₂₂ percarboxylicacid has a concentration from about 0.1 ppm to about 10,000 ppm, e.g.,about 0.1-1 ppm, 1-10 ppm, 10-20 ppm, 20-30 ppm, 30-40 ppm, 40-50 ppm,50-60 ppm, 60-70 ppm, 70-80 ppm, 80-90 ppm, 90-100 ppm, 100-150 ppm,150-200 ppm, 200-250 ppm, 250-300 ppm, 300-350 ppm, 350-400 ppm, 400-450ppm, 450-500 ppm, 500-550 ppm, 550-600 ppm, 600-650 ppm, 650-700 ppm,700-750 ppm, 750-800 ppm, 800-850 ppm, 850-900 ppm, 900-950 ppm,950-1,000 ppm, 1,000-1,500 ppm, 1,500-2,000 ppm, 2,000-2,500 ppm,2,500-3,000 ppm, 3,000-3,500 ppm, 3,500-4,000 ppm, 4,000-4,500 ppm, or4,500-5,000 ppm, 5,000-5,500 ppm, 5,500-6,000 ppm, 6,000-6,500 ppm,6,500-7,000 ppm, 7,000-7,500 ppm, 7,500-8,000, 8,000-8,500 ppm,8,500-9,000 ppm, 9,000-9,500 ppm, or 9,500-10,000 ppm.

Additional Optional Materials

The present compositions can optionally include additional ingredientsto enhance the composition for water treatment according to theinvention, including for example, friction reducers, viscosity enhancersand the like. Additional optional functional ingredients may include forexample, peracid stabilizers, emulsifiers, corrosion inhibitors and/ordescaling agents (i.e. scale inhibitors), surfactants and/or additionalantimicrobial agents for enhanced efficacy (e.g. mixed peracids,biocides), antifoaming agents, acidulants (e.g. strong mineral acids),additional carboxylic acids, surfactants, anti-redeposition agents,builders, and the like. In an embodiment, no additional functionalingredients are employed.

Anti-Redeposition Agents

The present compositions or cleaning use solutions can include ananti-redeposition agent capable of facilitating sustained suspension ofsoils in a cleaning solution and preventing the removed soils from beingredeposited onto the substrate being cleaned. Examples of suitableanti-redeposition agents include fatty acid amides, fluorocarbonsurfactants, complex phosphate esters, styrene maleic anhydridecopolymers, and cellulosic derivatives such as hydroxyethyl cellulose,hydroxypropyl cellulose, and the like. A use solution can include0.005-10 wt %, or 0.1-5 wt %, of an anti-redeposition agent.

Builders

The present compositions or cleaning use solutions can include abuilder. Builders include chelating agents (chelators), sequesteringagents (sequestrants), and the like. The builder may act to stabilizethe cleaning composition or use solution. Examples of builders include,but are not limited to, phosphonates, phosphates, aminocarboxylates andtheir derivatives, pyrophosphates, polyphosphates, ethylenediamene andethylenetriamene derivatives, hydroxyacids, and mono-, di-, andtri-carboxylates and their corresponding acids. Other exemplary buildersinclude aluminosilicates, nitroloacetates and their derivatives, andmixtures thereof. Still other exemplary builders includeaminocarboxylates, including salts of ethylenediaminetetraacetic acid(EDTA), hydroxyethylenediaminetetraacetic acid (HEDTA), anddiethylenetriaminepentaacetic acid. For a further discussion ofchelating agents/sequestrants, see Kirk-Othmer, Encyclopedia of ChemicalTechnology, Third Edition, volume 5, pages 339-366 and volume 23, pages319-320, which is incorporated in its entirety. According to an aspectof the invention, preferred builders are water soluble, biodegradableand phosphorus-free. The amount of builder in the cleaning compositionor use solution, if present, is typically between about 10 ppm and about1000 ppm in the cleaning composition or use solution.

Friction Reducers

Friction reducers are used in water or other water-based fluids used inhydraulic fracturing treatments for subterranean well formations inorder to improve permeability of the desired gas and/or oil beingrecovered from the fluid-conductive cracks or pathways created throughthe fracking process. The friction reducers allow the water to be pumpedinto the formations more quickly. Various polymer additives have beenwidely used as friction reducers to enhance or modify thecharacteristics of the aqueous fluids used in well drilling, recoveryand production applications.

Examples of commonly used friction reducers include polyacrylamidepolymers and copolymers. In an aspect, additional suitable frictionreducers may include acrylamide-derived polymers and copolymers, such aspolyacrylamide (sometime abbreviated as PAM), acrylamide-acrylate(acrylic acid) copolymers, acrylic acid-methacrylamide copolymers,partially hydrolyzed polyacrylamide copolymers (PHPA), partiallyhydrolyzed polymethacrylamide, acrylamide-methyl-propane sulfonatecopolymers (AMPS) and the like. Various derivatives of such polymers andcopolymers, e.g., quaternary amine salts, hydrolyzed versions, and thelike, should be understood to be included with the polymers andcopolymers described herein.

Friction reducers are combined with water and/or other aqueous fluids,which in combination are often referred to as “slick water” fluids.Slick water fluids have reduced frictional drag and beneficial flowcharacteristics which enable the pumping of the aqueous fluids intovarious gas- and/or oil-producing areas, including for example forfracturing.

In an aspect of the invention, a friction reducer is present in a usesolution in an amount between about 1 ppm to about 1,000 ppm, or fromabout 100 ppm to 1,000 ppm. In a further aspect, a friction reducer ispresent in a use solution in an amount of at least about 0.01 wt-% toabout 10 wt-%, preferably at least about 0.01 wt-% to about 5 wt-%,preferably at least about 0.01 wt-% to about 1 wt-%, more preferably atleast about 0.01 wt-% to about 0.5 wt-%, and still more preferably atleast about 0.01 wt-% to about 0.1 wt-%. Beneficially, the compositionsand methods of the invention do not negatively interfere with frictionreducers included in an aqueous solution.

Viscosity Enhancers

Viscosity enhancers are additional polymers used in water or otherwater-based fluids used in hydraulic fracturing treatments to provideviscosity enhancement. Natural and/or synthetic viscosity-increasingpolymers may be employed in compositions and methods according to theinvention. Viscosity enhancers may also be referred to as gelling agentsand examples include guar, xanthan, cellulose derivatives andpolyacrylamide and polyacrylate polymers and copolymers, and the like.

In an aspect of the invention, a viscosity enhancer is present in a usesolution in an amount between about 1 ppm to about 1,000 ppm, or fromabout 100 ppm to 1,000 ppm. In a further aspect, a viscosity enhancer ispresent in a use solution in an amount of at least about 0.01 wt-% toabout 10 wt-%, preferably at least about 0.01 wt-% to about 5 wt-%,preferably at least about 0.01 wt-% to about 1 wt-%, at least about 0.01wt-% to about 2 wt-%, preferably at least about 0.01 wt-% to about 1wt-%, preferably at least about 0.01 wt-% to about 0.5 wt-%.Beneficially, the compositions and methods of the invention do notnegatively interfere with viscosity enhancer included in an aqueoussolution.

Corrosion Inhibitors

Corrosion inhibitors are additional molecules used in oil and gasrecovery operations. Corrosion inhibitors that may be employed in thepresent disclosure include the exemplary corrosion inhibitors disclosedin U.S. Pat. Nos. 3,909,447, 4,443,609, 5,965,785 and 9,150,793, GB Pat.No. 1,198,734, WO/03/006581, WO04/044266, and WO08/005058, eachincorporated herein by reference in their entireties.

In some embodiments, the corrosion inhibitor can be a phosphate ester, aderivative of the phosphate ester, a diacid, a derivative of the diacid,a quat amine, a derivative of the quat amine, an imidazoline, aderivative of the imidazoline, an alkyl pyridine, a derivative of thealkyl pyridine, a phosphonium salt, a derivative of the phosphoniumsalt, or a combination thereof.

In an embodiment, the corrosion inhibitors include neutralizing amines.Suitable neutralization amines include morpholine, methoxypropylamine,ethyienediamine, monoethanolalmine, dimethylethanolaminediethylhydroxylamine, and hydrazine didrates.

In an embodiment, the corrosion inhibitors include cationic surfactantcomprising an ammonium halide. The ammonium halide may include anysuitable types of ammonium halides. In embodiments, the ammonium halidesinclude alkyl ammonium halides, polyalkyl ammonium halides, benzyltriethyl ammonium halides or any combinations thereof. In embodiments,the cationic surfactant includes any combination or at least one of analkyl trimethyl ammonium halide, alkyl triethyl ammonium halide, analkyl dimethyl benzyl ammonium halide, and one or more imidazoliniumhalides.

In an embodiment, the corrosion inhibitors include phosphonates,including phosphonic acid and esters, such as tetrahydrothiazolesphosphonic acids or esters. Additional phosphorus-based compounds may besuitable for use, including thiophosphonic acid and the salts and alkyl,and aryl esters of the same.

In an aspect of the invention, a corrosion inhibitor is present in a usesolution in an amount between about 1 ppm to 50,000 ppm. In a furtheraspect, a corrosion inhibitor is present in a use solution in an amountof at least about 0.0001 wt-% to about 20 wt-%, preferably at leastabout 0.0001 wt-% to about 10 wt-%, preferably at least about 0.0001wt-% to about 5 wt-%, preferably at least about 0.0001 wt-% to about 1wt-%, preferably at least about 0.0001 wt-% to about 0.1 wt-%, and stillmore preferably at least about 0.0001 wt-% to about 0.05 wt-%.

Beneficially, the compositions and methods of the invention do notnegatively interfere with corrosion inhibitor included in an aqueoussolution. As a further benefit, the use of the two-part peroxycarboxylicacid forming compositions according to the invention allow formulationof the corrosion inhibitors directly into either of the premixformulations, overcoming a substantial limitation of the prior artwherein conventional corrosion inhibitors are not sufficiently stable inother equilibrium chemistries. The two-part premixes according toembodiments of the invention allow formulation of the corrosioninhibitors directly into a premix and thereby reducing the number ofinputs required for a system to be treated according to the methods andchemistries of the present invention.

Scale Inhibitors

Scale inhibitors are additional molecules used in oil and gas recoveryoperations. Common scale inhibitors that may be employed in these typesof applications include polymers and co-polymers, phosphates, phosphateesters and the like.

In an aspect of the invention, a scale inhibitor is present in a usesolution in an amount between about 1 ppm to about 5,000 ppm, or fromabout 100 ppm to 5,000 ppm. In a further aspect, a scale inhibitor ispresent in a use solution in an amount of at least about 0.0001 wt-% toabout 10 wt-%, at least about 0.0001 wt-% to about 1 wt-%, preferably atleast about 0.0001 wt-% to about 0.1 wt-%, preferably at least about0.0001 wt-% to about 0.05 wt-%. Beneficially, the compositions andmethods of the invention do not negatively interfere with scaleinhibitor included in an aqueous solution.

Additional Antimicrobial Agents

Additional antimicrobial agents may be included in the compositionsand/or methods of the invention for enhanced antimicrobial efficacy. Inaddition to the use of peracid compositions, additional antimicrobialagents and biocides may be employed. Additional biocides may include,for example, a quaternary ammonium compound as disclosed in U.S. Pat.No. 6,627,657, which is incorporated herein by reference in itsentirety. Beneficially, the presence of the quaternary ammonium compoundprovides both synergistic antimicrobial efficacies with peracids, aswell as maintains long term biocidal efficacy of the compositions.

In another embodiment, the additional biocide may include an oxidizercompatible phosphonium biocide, such as tributyl tetradecyl phosphoniumchloride. The phosphonium biocide provides similar antimicrobialadvantages as the quaternary ammonium compound in combination with theperacids. In addition, the phosphonium biocide is compatible with theanionic polymeric chemicals commonly used in the oil field applications,such as the methods of the fracking disclosed according to theinvention.

Additional antimicrobial and biocide agents may be employed in amountssufficient to provide antimicrobial efficacy, as may vary depending uponthe water source in need of treatment and the contaminants therein. Suchagents may be present in a use solution in an amount of at least about0.1 wt-% to about 5 wt-%, preferably at least about 0.1 wt-% to about 2wt-%, more preferably from about 0.1 wt-% to about 1 wt-%.

Acidulants

Acidulants may be included as additional functional ingredients in acomposition according to the invention. In an aspect, a strong mineralacid such as nitric acid or sulfuric acid can be used to treat watersources, as disclosed in U.S. Pat. No. 4,587,264, which is incorporatedherein by reference in its entirety. The combined use of a strongmineral acid with the peracid composition provides enhancedantimicrobial efficacy as a result of the acidity assisting in removingchemical contaminants within the water source (e.g. sulfite and sulfidespecies). In addition, some strong mineral acids, such as nitric acid,provide a further benefit of reducing the risk of corrosion towardmetals contacted by the peracid compositions according to the invention.In some embodiments, the present composition does not comprise a mineralacid or a strong mineral acid.

Acidulants may be employed in amounts sufficient to provide the intendedantimicrobial efficacy and/or anticorrosion benefits, as may varydepending upon the water source in need of treatment and thecontaminants therein. Such agents may be present in a use solution in anamount of at least about 0.1 wt-% to about 10 wt-%, preferably at leastabout 0.1 wt-% to about 5 wt-%, more preferably from about 0.1 wt-% toabout 1 wt-%.

Catalase and Peroxidase Enzyme

In an aspect of the invention, a catalase or peroxidase enzyme can beused to reduce and/or eliminate the concentration of hydrogen peroxidein an antimicrobial peracid composition. The enzymes catalyze thedecomposition of hydrogen peroxide to water and oxygen. Beneficially,the reduction and/or elimination of hydrogen peroxide (strong oxidizer)results in other additives for a water treatment source (e.g. watersource) not being degraded or rendered incompatible. Various additivesused to enhance or modify the characteristics of the aqueous fluids usedin well drilling, recovery and production applications are at risk ofdegradation by the oxidizing effects of hydrogen peroxide. These mayinclude for example, friction reducers and viscosity enhancers used incommercial well drilling, well completion and stimulation, or productionapplications.

Various sources of catalase enzymes may be employed according to theinvention, including: animal sources such as bovine catalase isolatedfrom beef livers; fungal catalases isolated from fungi includingPenicillium chrysogenum, Penicillium notatum, and Aspergillus niger;plant sources; bacterial sources such as Staphylcoccus aureus, andgenetic variations and modifications thereof. In an aspect of theinvention, fungal catalases are utilized to reduce the hydrogen peroxidecontent of a peracid composition. Catalases are commercially availablein various forms, including liquid and spray dried forms. Commerciallyavailable catalase includes both the active enzyme as well as additionalingredients to enhance the stability of the enzyme. Some exemplarycommercially available catalase enzymes include Genencor CA-100 andCA-400, as well as Mitsubishi Gas and Chemical (MGC) ASC super G and ASCsuper 200, and Optimase CA 400L from Genecor International. Additionaldescription of suitable catalase enzymes are disclosed and hereinincorporated by reference in its entirety from U.S. Patent PublicationNo. 2009/0269324.

In an aspect of the invention, catalase enzymes have a high ability todecompose hydrogen peroxide. Beneficially, the reduction or eliminationof hydrogen peroxide from oxidizing compositions obviates the variousdetriments caused by oxidizing agents. In particular, the use ofcatalase with the peracids compositions provides enhanced antimicrobialbenefits without causing the damage associated with conventionaloxidizing agents (e.g. peracetic acid, hypochlorite or hypochlorousacid, and/or chlorine dioxide), such as corrosion.

Peroxidase enzymes may also be employed to decompose hydrogen peroxidefrom a peracid composition. Although peroxidase enzymes primarilyfunction to enable oxidation of substrates by hydrogen peroxide, theyare also suitable for effectively lowering hydrogen peroxide to peracidratios in compositions. Various sources of peroxidase enzymes may beemployed according to the invention, including for example animalsources, fungal peroxidases, and genetic variations and modificationsthereof. Peroxidases are commercially available in various forms,including liquid and spray dried forms. Commercially availableperoxidases include both the active enzyme as well as additionalingredients to enhance the stability of the enzyme.

In some embodiments, the catalase or peroxidase enzyme is able todegrade at least about 50% of the initial concentration of hydrogenperoxide in a peracid composition. Preferably, the enzyme is provided insufficient amount to reduce the hydrogen peroxide concentration of aperacid composition by at least more than about 50%, more preferably atleast about 60%, at least about 70%, at least about 80%, at least about90%. In some embodiments, the enzyme reduces the hydrogen peroxideconcentration of a peracid composition by more than 90%.

In an aspect of the invention, the enzymes are suitable for use and havea tolerance to a wide range of temperatures, including the temperaturesranges in water treatment applications which may range from about 0-80°C. A suitable catalase enzyme will maintain at least 50% of its activityunder such storage and/or application temperatures for at least about 10minutes, preferably for at least about 1 hour.

In a further aspect of the invention, the catalase or peroxidase enzymesdescribed herein have a tolerance to pH ranges found in water treatmentapplications. Acetic acid concentrations (or other carboxylic acid) in awater treatment application can widely range in parts per million (ppm)of acetic or other carboxylic acid. The solutions may have acorresponding range of pH range from greater than 0 to about 10. Asuitable catalase or peroxidase enzyme will maintain at least about 50%of its activity in such solutions of acetic or other carboxylic acidover a period of about 10 minutes.

In an aspect of the invention, a catalase or peroxidase enzyme ispresent in a use solution of the water treatment and peracid compositionin sufficient amounts to reduce the concentration of hydrogen peroxidefrom the peracid composition by at least 50% within about 10 minutes,preferably within about 5 minutes, preferably within about 2 to 5minutes, more preferably within about 1 minute. The ranges ofconcentration of the enzymes will vary depending upon the amount of timewithin which 50% of the hydrogen peroxide from the peracid compositionis removed. In certain aspects of the invention, a catalase orperoxidase enzyme is present in a use solution composition including thewater source to be treated in amounts between about 1 ppm and about1,000 ppm, preferably between about 5 ppm and 500 ppm, and morepreferably between about 10 ppm and about 100 ppm.

Surfactants

In some embodiments, the cleaning compositions employed by the method ofcleaning include a surfactant. Beneficially, surfactants improve soilremoval and can further be used to prevent the buildup of largequantities of foam generated by soils under alkaline conditions. Thesurfactant chosen can be compatible with the surface to be cleaned. Avariety of surfactants can be used, including anionic, nonionic,cationic, and zwitterionic surfactants, which are commercially availablefrom a number of sources. Suitable surfactants include nonionicsurfactants, for example, low foaming non-ionic surfactants. For adiscussion of surfactants, see Kirk-Othmer, Encyclopedia of ChemicalTechnology, Third Edition, volume 8, pages 900-912, which isincorporated in its entirety.

Peracids are known to be strong oxidation agents, and as a result manychemicals, including commonly used surfactants are not compatible withconcentrated peracids for extended presence of peracids. While it isideal to use surfactants along with peracids to deliver preferredperformance, such as cleaning, wetting et al., there is very limitedchoice of surfactants that could be put in preformed peracidformulations that meet the minimum shelf life requirements forcommercial use. For examples, nonionic surfactants will be degraded byperacids, and cationic surfactants with halogen counter anions willdecompose peracids. Some anionic surfactants, namely non substitutedalkyl sulfonates, such as linear alkylbenzenesulfonate, lineralkylsulfonate are more compatible with peracids and maybe used in someperacids compositions, but these anionic surfactants may not deliver thedesired performance owing to their unwanted properties, such as highfoam, water hardness tolerance as well as regulation requirements. Incontrast, for onsite generated peracid compositions such as disclosed inthe present art, all surfactants described above could be coexist withthe peracids, as the generated peracids are only stored for very limitedtime, and typically in hours at the most, and the reactions between thesurfactants and the peracids are not significant.

In particular embodiments of the invention, the method of cleaning isdirected to brewery surfaces. The soils encountered in brewery surfacesalready contain components that are moderate to high foaming. Thus, insuch an application, it may be desirous to use a low foaming surfactantor wetting agent to provide wetting properties and better cleaningeffectiveness. Examples of various suitable surfactants for such breweryapplications include those disclosed in U.S. Patent Publication2014/0261546, which is herein incorporated by reference in its entirety.

Nonionic surfactants suitable for use in the methods of the presentinvention include, but are not limited to, those having a polyalkyleneoxide polymer as a portion of the surfactant molecule. Exemplarynonionic surfactants include, but are not limited to, chlorine-,benzyl-, methyl-, ethyl-, propyl-, butyl- and other like alkyl-cappedpolyethylene and/or polypropylene glycol ethers of fatty alcohols;polyalkylene oxide free nonionics such as alkyl polyglycosides; sorbitanand sucrose esters and their ethoxylates; alkoxylated ethylene diamine;carboxylic acid esters such as glycerol esters, polyoxyethylene esters,ethoxylated and glycol esters of fatty acids; carboxylic amides such asdiethanolamine condensates, monoalkanolamine condensates,polyoxyethylene fatty acid amides; and ethoxylated amines and etheramines commercially available from Tomah Corporation and other likenonionic compounds. In some embodiments sugar ester based nonionicsurfactants are preferred, including for example sorbitan and sucroseesters, such as those commercially available as Polysorbate 60,Polysorbate 80, sorbitan octanoate, and the like. In other embodiments,polyglycerol fatty acid ester surfactants are preferred.

Additional exemplary nonionic surfactants suitable for use in themethods of the present invention, include, but are not limited to, thosehaving a polyalkylene oxide polymer portion include nonionic surfactantsof C6-C24 alcohol ethoxylates (e.g., C6-C14 alcohol ethoxylates) having1 to about 20 ethylene oxide groups (e.g., about 9 to about 20 ethyleneoxide groups); C6-C24 alkylphenol ethoxylates (e.g., C8-C.sub. 10alkylphenol ethoxylates) having 1 to about 100 ethylene oxide groups(e.g., about 12 to about 20 ethylene oxide groups); C6-C24alkylpolyglycosides (e.g., C6-C20 alkylpolyglycosides) having 1 to about20 glycoside groups (e.g., about 9 to about 20 glycoside groups); C6-C24fatty acid ester ethoxylates, propoxylates or glycerides; and C4-C24mono or dialkanolamides. In some embodiments ethoxylated mono anddiglyceride nonionic surfactants are preferred.

Suitable surfactants may also include food grade surfactants, linearalkylbenzene sulfonic acids and their salts, and ethyleneoxide/propylene oxide derivatives sold under the Pluronic trade name.Suitable surfactants include those that are compatible as an indirect ordirect food additive or substance.

Anionic surfactants suitable for use with the disclosed methods may alsoinclude, for example, carboxylates such as alkylcarboxylates (carboxylicacid salts) and polyalkoxycarboxylates, alcohol ethoxylate carboxylates,nonylphenol ethoxylate carboxylates, and the like; sulfonates such asalkylsulfonates, alkylbenzenesulfonates, alkylarylsulfonates, sulfonatedfatty acid esters, and the like; sulfates such as sulfated alcohols,sulfated alcohol ethoxylates, sulfated alkylphenols, alkylsulfates,sulfosuccinates, alkylether sulfates, and the like; and phosphate esterssuch as alkylphosphate esters, and the like. Exemplary anionics include,but are not limited to, sodium alkylarylsulfonate, alpha-olefinsulfonate, and fatty alcohol sulfates. Examples of suitable anionicsurfactants include sodium dodecylbenzene sulfonic acid, potassiumlaureth-7 sulfate, and sodium tetradecenyl sulfonate.

In some embodiments, the surfactant includes linear alkyl benzenesulfonates, alcohol sulfonates, amine oxides, linear and branchedalcohol ethoxylates, alkyl polyglucosides, alkyl phenol ethoxylates,polyethylene glycol esters, EO/PO block copolymers and combinationsthereof. In other embodiments, alkyl linear benzene sulfonate anionicsurfactants are preferred.

The surfactants described herein can be used singly or in combination inthe methods of the present invention. In particular, the nonionics andanionics can be used in combination. The semi-polar nonionic, cationic,amphoteric and zwitterionic surfactants can be employed in combinationwith nonionics or anionics. The above examples are merely specificillustrations of the numerous surfactants which can find applicationwithin the scope of this invention. It should be understood that theselection of particular surfactants or combinations of surfactants canbe based on a number of factors including compatibility with the surfaceto be cleaned at the intended use concentration and the intendedenvironmental conditions including temperature and pH.

In addition, the level and degree of foaming under the conditions of useand in subsequent recovery of the composition can be a factor forselecting particular surfactants and mixtures of surfactants. Forexample, in certain applications it may be desirable to minimize foamingand a surfactant or mixture of surfactants that provides reduced foamingcan be used. In addition, it may be desirable to select a surfactant ora mixture of surfactants that exhibits a foam that breaks downrelatively quickly so that the composition can be recovered and reusedwith an acceptable amount of down time. In addition, the surfactant ormixture of surfactants can be selected depending upon the particularsoil that is to be removed.

It should be understood that the compositions for use with the methodsof the present invention need not include a surfactant or a surfactantmixture, and can include other components. In addition, the compositionscan include a surfactant or surfactant mixture in combination with othercomponents. In some embodiments, the cleaning compositions and usesolutions employed by the method of cleaning include about 0.005 wt. %to about 5 wt. % of a surfactant. In particular embodiments of thepresent invention, the surfactant comprises between about 0.005 wt. % toabout 0.02 wt. % of the cleaning composition or use solution. In anotheraspect of the invention, the surfactant comprises between about 0.5 wt.% and about 1.0 wt. % of the cleaning composition or use solution. Insome embodiments, the compositions of the present invention includeabout 50 ppm to about 200 ppm of a surfactant.

In some embodiments, the amount of surfactant in the cleaningcomposition is about 0.0001 wt % to about 1.0 wt %. Acceptable levels ofsurfactant include about 0.001 wt % to about 1 wt %, or about 0.002 wt %to about 0.05 wt %. It is to be understood that all values and rangesbetween these values and ranges are encompassed by the methods of thepresent invention.

Methods for Treating a Target

In still another aspect, the present invention is directed to a methodfor treating a target, which method comprises contacting a target withan effective amount of peroxyformic acid formed using the above methodsto form a treated target composition, wherein said treated targetcomposition comprises from about 0.1 ppm to about 10,000 ppm of saidperoxyformic acid, and preferably, said contacting lasts for sufficienttime to stabilize or reduce microbial population in and/or on saidtarget or said treated target composition.

The peroxyformic acid and the target can be contacted to form a treatedtarget composition comprising any suitable concentration of saidperoxyformic acid, e.g., about 0.1-10,000 ppm or any range therein, orpreferably from about 0.5-5,000 ppm, including about 0.1-1 ppm, 0.5-1ppm, 1-10 ppm, 10-20 ppm, 20-30 ppm, 30-40 ppm, 40-50 ppm, 50-60 ppm,60-70 ppm, 70-80 ppm, 80-90 ppm, 90-100 ppm, 100-150 ppm, 150-200 ppm,200-250 ppm, 250-300 ppm, 300-350 ppm, 350-400 ppm, 400-450 ppm, 450-500ppm, 500-550 ppm, 550-600 ppm, 600-650 ppm, 650-700 ppm, 700-750 ppm,750-800 ppm, 800-850 ppm, 850-900 ppm, 900-950 ppm, 950-1,000 ppm,1,000-1,500 ppm, 1,500-2,000 ppm, 2,000-2,500 ppm, 2,500-3,000 ppm,3,000-3,500 ppm, 3,500-4,000 ppm, 4,000-4,500 ppm, or 4,500-5,000 ppm,5,000-5,500 ppm, 5,500-6,000 ppm, 6,000-6,500 ppm, 6,500-7,000 ppm,7,000-7,500 ppm, 7,500-8,000, 8,000-8,500 ppm, 8,500-9,000 ppm,9,000-9,500 ppm, or 9,500-10,000 ppm of peroxyformic acid.

The composition used in the present methods can retain any suitableconcentration or percentage of the peroxyformic acid activity for anysuitable time after the treated target composition is formed. In someembodiments, the composition used in the present methods retains atleast about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% or 90% of the initialperoxyformic acid activity for any suitable time after the treatedtarget composition is formed. In other embodiments, the composition usedin the present methods retains at least about 60% of the initialperoxyformic acid activity for at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,11, 12, 13, 14, 15, 20, 25, 30 minutes, 1, 2, 5, 10, 15, 20 or 24 hours,or longer after the treated target composition is formed.

The present methods can be used to treat any suitable target. In someembodiments, the target is water, and the present methods can compriseproviding an effective amount of peroxyformic acid formed using theabove methods to a water source in need of treatment to form a treatedwater source, wherein said treated water source comprises from about 0.5ppm to about 5,000 ppm of said peroxyformic acid, e.g., about 0.1-1,000ppm or any range therein, or about 0.5-5,000 ppm or any range therein,including about 0.5-10 ppm, 1-10 ppm, 10-20 ppm, 20-30 ppm, 30-40 ppm,40-50 ppm, 50-60 ppm, 60-70 ppm, 70-80 ppm, 80-90 ppm, 90-100 ppm,100-150 ppm, 150-200 ppm, 200-250 ppm, 250-300 ppm, 300-350 ppm, 350-400ppm, 400-450 ppm, 450-500 ppm, 500-550 ppm, 550-600 ppm, 600-650 ppm,650-700 ppm, 700-750 ppm, 750-800 ppm, 800-850 ppm, 850-900 ppm, 900-950ppm, 950-1,000 ppm, or 1,000-5,000 ppm of peroxyformic acid.

The present methods can be used to treat any suitable water source. Forexample, a water source in need of treatment can be fresh water, pondwater, sea water, produced water, paper manufacturing water, tower wateror a combination thereof.

In some embodiments, the tower water is cooling water and the treatedwater source comprises from about 0.1 ppm to about 10 ppm of theperoxyformic acid, e.g., about 1-10 ppm or any range therein, includingabout 0.1-1 ppm, 1-2 ppm, 2-3 ppm, 3-4 ppm, 4-5 ppm, 5-6 ppm, 6-7 ppm,7-8 ppm, 8-9 ppm, or 9-10 ppm peroxyformic acid. The contacting step canlast any suitable amount of time, e.g., about 1-2 minutes, 2-3 minutes,3-4 minutes, 4-5 minutes, 5-6 minutes, 6-7 minutes, 7-8 minutes, 8-9minutes, or 9-10 minutes. The contacting step can be conducted atsuitable temperature range. For example, the contacting step can beconducted at a temperature ranging from about −2° C. to about 70° C.,e.g., about −2° C.-0° C., −1° C.-0° C., 0° C.-1° C., 1° C.-2° C., 2°C.-3° C., 3° C.-4° C., 4° C.-5° C., 5° C.-10° C., 10° C.-15° C., 15°C.-20° C., 20° C.-25° C., 25° C.-30° C., 30° C.-35° C., 35° C.-40° C.,40° C.-45° C., 45° C.-50° C., 50° C.-55° C., 55° C.-60° C., 60-65° C.,or 65° C.-70° C.

In some embodiments, the present methods can be used to treat a watersource used in oil and/or gas drilling operation. For example, thepresent methods can be used to treat a water source used in an operationof induced hydraulic fracturing (hydrofracturing or fracking). The watersource can comprise a friction reducer or a viscosity enhancer. Thepresent methods can be used to treat a water source to form a treatedwater source that comprises from about 0.1 ppm to about 10 ppm of theperoxyformic acid, e.g., about 1-10 ppm or any range therein, includingabout 1-2 ppm, 2-3 ppm, 3-4 ppm, 4-5 ppm, 5-6 ppm, 6-7 ppm, 7-8 ppm, 8-9ppm, or 9-10 ppm peroxyformic acid. The present methods can furthercomprise disposing of the treated water source. The present methods canfurther comprise directing the treated water source into a subterraneanenvironment, e.g., a subterranean environment that comprises a well in agas and/or oil.

In some embodiments, the target to be treated by the present methods canbe water and/or at least a portion of a medium, a container, anequipment, a system or a facility for producing, holding, processing,packaging, storing, or transporting pulp. The present methods can beused to treat water and/or other target(s) for any suitable purpose. Forexample, the present methods can be used in papermaking, textiles, food,or pharmaceutical industry. The present methods can be used to treat awater source, alone or in combination with other target(s), to form atreated water source that comprises any suitable concentration ofperoxyformic acid, e.g., about 0.5-30 ppm or any range therein,including about 1-2 ppm, 2-3 ppm, 3-4 ppm, 4-5 ppm, 5-6 ppm, 6-7 ppm,7-8 ppm, 8-9 ppm, 9-10 ppm, 10-15 ppm, 15-20 ppm, 20-25 ppm, or 25-30ppm of peroxyformic acid.

In some embodiments, the present methods can be used to reduce or removeH₂S in a treated water source. The present methods can be used to reduceor remove H₂S at any suitable rate. For example, H₂S can be reduced orremoved at a rate similar to that as achieved by using a comparableamount of triazine. The present methods can be used to reduce or removeH₂S in any suitable treated water source. For example, the treated watersource can be a treated produced water. The peroxyformic acid can beused at any suitable concentration, e.g., about 0.1-1,000 ppm or anyrange therein, including about 1-10 ppm, 10-20 ppm, 20-30 ppm, 30-40ppm, 40-50 ppm, 50-60 ppm, 60-70 ppm, 70-80 ppm, 80-90 ppm, 90-100 ppm,100-150 ppm, 150-200 ppm, 200-250 ppm, 250-300 ppm, 300-350 ppm, 350-400ppm, 400-450 ppm, 450-500 ppm, 500-550 ppm, 550-600 ppm, 600-650 ppm,650-700 ppm, 700-750 ppm, 750-800 ppm, 800-850 ppm, 850-900 ppm, 900-950ppm, 950-1,000 ppm of peroxyformic acid.

In some embodiments, the present methods can be used to reduce or removeiron sulfide in a treated water source. The present methods can be usedto reduce or remove iron sulfide in a treated water source at anysuitable rate or within any suitable time. For example, the iron sulfidecan be reduced or removed within about one hour of the treatment. Thepresent methods can be used to reduce or remove iron sulfide in anysuitable treated water source. For example, the treated water source isa treated produced water. The peroxyformic acid can be used at anysuitable concentration, e.g., about 0.1-1,000 ppm or any range therein,including about 1-10 ppm, 10-20 ppm, 20-30 ppm, 30-40 ppm, 40-50 ppm,50-60 ppm, 60-70 ppm, 70-80 ppm, 80-90 ppm, 90-100 ppm, 100-150 ppm,150-200 ppm, 200-250 ppm, 250-300 ppm, 300-350 ppm, 350-400 ppm, 400-450ppm, 450-500 ppm, 500-550 ppm, 550-600 ppm, 600-650 ppm, 650-700 ppm,700-750 ppm, 750-800 ppm, 800-850 ppm, 850-900 ppm, 900-950 ppm,950-1,000 ppm of peroxyformic acid.

In some embodiments, the present methods can be used to improve clarityof a treated water source. The present methods can be used to improveclarity of a treated water source in any suitable manner. For example,the present methods can be used to improve clarity of a treated watersource by oxidizing a contaminant in the treated water source. Thepresent methods can be used to improve clarity of any suitable watersource. For example, the treated water source can be a treated producedwater. The peroxyformic acid can be used at any suitable concentration,e.g., about 0.5-1,000 ppm or any range therein, including about 1-10ppm, 10-20 ppm, 20-30 ppm, 30-40 ppm, 40-50 ppm, 50-60 ppm, 60-70 ppm,70-80 ppm, 80-90 ppm, 90-100 ppm, 100-150 ppm, 150-200 ppm, 200-250 ppm,250-300 ppm, 300-350 ppm, 350-400 ppm, 400-450 ppm, 450-500 ppm, 500-550ppm, 550-600 ppm, 600-650 ppm, 650-700 ppm, 700-750 ppm, 750-800 ppm,800-850 ppm, 850-900 ppm, 900-950 ppm, 950-1,000 ppm of peroxyformicacid.

In some embodiments, the present methods can be used to reduce the totaldissolved oxygen in a water source. The present methods can be used toreduce the total dissolved oxygen in any suitable treated water source.For example, the treated water source can be a treated produced water.The peroxyformic acid can be used at any suitable concentration. Forexample, the peroxyformic acid can be used at a concentration that is ator above its consumption rate in the treated water source. In anotherexample, the peroxyformic acid can be used at a concentration from about0.1 ppm to about 1,000 ppm, e.g., about 1-10 ppm, 10-20 ppm, 20-30 ppm,30-40 ppm, 40-50 ppm, 50-60 ppm, 60-70 ppm, 70-80 ppm, 80-90 ppm, 90-100ppm, 100-150 ppm, 150-200 ppm, 200-250 ppm, 250-300 ppm, 300-350 ppm,350-400 ppm, 400-450 ppm, 450-500 ppm, 500-550 ppm, 550-600 ppm, 600-650ppm, 650-700 ppm, 700-750 ppm, 750-800 ppm, 800-850 ppm, 850-900 ppm,900-950 ppm, 950-1,000 ppm of peroxyformic acid.

In some embodiments, a water source can be treated with the peroxyformicacid so that the treated water source has a lower corrosion ratecompared to a water source treated with a C₂-C₂₂ percarboxylic acid. Forexample, a water source can be treated with the peroxyformic acid at aconcentration at its consumption rate, the treated water source can havea lower corrosion rate compared to a water source treated with a C₂-C₂₂percarboxylic acid at a concentration at its consumption rate. Anysuitable water source can be treated with the peroxyformic acid so thatthe treated water source has a lower corrosion rate compared to a watersource treated with a C₂-C₂₂ percarboxylic acid. For example, thetreated water source can be a treated produced water. The peroxyformicacid can be used at any suitable concentration, e.g., about 0.1-1,000ppm or any range therein, including about 1-10 ppm, 10-20 ppm, 20-30ppm, 30-40 ppm, 40-50 ppm, 50-60 ppm, 60-70 ppm, 70-80 ppm, 80-90 ppm,90-100 ppm, 100-150 ppm, 150-200 ppm, 200-250 ppm, 250-300 ppm, 300-350ppm, 350-400 ppm, 400-450 ppm, 450-500 ppm, 500-550 ppm, 550-600 ppm,600-650 ppm, 650-700 ppm, 700-750 ppm, 750-800 ppm, 800-850 ppm, 850-900ppm, 900-950 ppm, 950-1,000 ppm of peroxyformic acid.

The present methods can further comprise contacting the target with acorrosion inhibitor. Any suitable corrosion inhibitor can be used. Insome embodiments, the corrosion inhibitor can be a phosphate ester, aderivative of the phosphate ester, a diacid, a derivative of the diacid,a quat amine, a derivative of the quat amine, an imidazoline, aderivative of the imidazoline, an alkyl pyridine, a derivative of thealkyl pyridine, a phosphonium salt, a derivative of the phosphoniumsalt, or a combination thereof.

The corrosion inhibitor can be used at any suitable concentration. Insome embodiments, the corrosion inhibitor can be used at a concentrationfrom about 0.5 ppm to about 50,000 ppm, e.g., about 1-10 ppm, 10-20 ppm,20-30 ppm, 30-40 ppm, 40-50 ppm, 50-60 ppm, 60-70 ppm, 70-80 ppm, 80-90ppm, 90-100 ppm, 100-150 ppm, 150-200 ppm, 200-250 ppm, 250-300 ppm,300-350 ppm, 350-400 ppm, 400-450 ppm, 450-500 ppm, 500-550 ppm, 550-600ppm, 600-650 ppm, 650-700 ppm, 700-750 ppm, 750-800 ppm, 800-850 ppm,850-900 ppm, 900-950 ppm, 950-1,000 ppm, 1,000-1,500 ppm, 1,500-2,000ppm, 2,000-2,500 ppm, 2,500-3,000 ppm, 3,000-3,500 ppm, 3,500-4,000 ppm,4,000-4,500 ppm, or 4,500-5,000 ppm, 5,000-5,500 ppm, 5,500-6,000 ppm,6,000-6,500 ppm, 6,500-7,000 ppm, 7,000-7,500 ppm, 7,500-8,000,8,000-8,500 ppm, 8,500-9,000 ppm, 9,000-9,500 ppm, 9,500-10,000, or10,000-50,000 ppm. In other embodiments, the ratio between theconcentration of the peroxyformic acid (w/v) and the concentration ofthe corrosion inhibitor (w/v) used in the present method can be fromabout 0.01 to about 100, e.g., about 0.01-0.05, 0.05-0.1, 0.1-0.5,0.5-1, 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10, 10-15, 15-20,20-25, 25-30, 30-35, 35-40, 40-45, 45-50, 50-60, 60-70, 70-80, 80-90,90-100. In still other embodiments, the corrosion inhibitor has asynergistic effect with the peroxyformic acid to stabilize or reducemicrobial population in and/or on the target or the treated targetcomposition. In yet other embodiments, the corrosion inhibitor can beused at a concentration that reduces acid corrosion in and/or on thetarget or the treated target composition. In yet other embodiments, thecorrosion inhibitor has a synergistic effect with the peroxyformic acidto stabilize or reduce microbial population in and/or on the target orthe treated target composition and reduces acid corrosion in and/or onthe target or the treated target composition.

The target can be contacted with the corrosion inhibitor at any suitabletime. In some embodiments, the target can be contacted with thecorrosion inhibitor before the target is contacted with the peroxyformicacid. In other embodiments, the target can be contacted with thecorrosion inhibitor after the target is contacted with the peroxyformicacid. In still other embodiments, the target can be contacted with thecorrosion inhibitor concurrently when the target is contacted with theperoxyformic acid, e.g., the corrosion inhibitor can be comprised in theperoxyformic acid composition formed by the methods described above.

In some embodiments, the target to be treated by the present methods canbe a food item or a plant item and/or at least a portion of a medium, acontainer, an equipment, a system or a facility for growing, holding,processing, packaging, storing, transporting, preparing, cooking orserving the food item or the plant item. Any suitable concentration ofperoxyformic acid can be used in the present methods. For example, theperoxyformic acid can be used at a concentration from about 0.1 ppm toabout 100 ppm, e.g., about 1-2 ppm, 2-3 ppm, 3-4 ppm, 4-5 ppm, 5-6 ppm,6-7 ppm, 7-8 ppm, 8-9 ppm, 9-10 ppm, 10-15 ppm, 15-20 ppm, 20-25 ppm, or25-30 ppm, 30-40 ppm, 40-50 ppm, 50-60 ppm, 60-70 ppm, 70-80 ppm, 80-90ppm, 90-100 ppm of peroxyformic acid. In some embodiments, the target isa food item or a plant item and the contacting step minimizes or doesnot induce an organoleptic effect in and/or on the food item or a plantitem.

The present methods can be used for treating any suitable plant item. Insome embodiments, the plant item is a grain, fruit, vegetable or flowerplant item. In other embodiments, the plant item is a living plant itemor a harvested plant item. In still other embodiments, the plant itemcomprises a seed, a tuber, a growing plant, a cutting, or a root stock.In yet other embodiments, the present methods are used for treating aliving plant tissue comprising treating the plant tissue with the abovecomposition in a diluted concentration to stabilize or reduce microbialpopulation in and/or on the plant tissue. In yet other embodiments, thepresent methods are used for growing a plant on a hydroponic substratein a hydroponic liquid supply medium, comprising: (a) establishing agrowing and living plant tissue in the hydroponic substrate; (b)contacting the living plant tissue, the hydroponic substrate and thehydroponic liquid with a composition of the present invention tostabilize or reduce microbial population in and/or on the living planttissue; and (c) harvesting a usable plant product with reduced microbialcontamination.

The present methods can be used for treating any suitable food item. Forexample, the food item can be an animal product, e.g., an animal carcassor an egg, a fruit item, a vegetable item, or a grain item. In someembodiments, the animal carcass can be a beef, pork, veal, buffalo,lamb, fish, sea food or poultry carcass. In other embodiments, the seafood carcass can be scallop, shrimp, crab, octopus, mussel, squid orlobster. In still other embodiments, the fruit item can be a botanicfruit, a culinary fruit, a simple fruit, an aggregate fruit, a multiplefruit, a berry, an accessory fruit or a seedless fruit. In yet otherembodiments, the vegetable item can be a flower bud, a seed, a leaf, aleaf sheath, a bud, a stem, a stem of leaves, a stem shoot, a tuber, awhole-plant sprout, a root or a bulb. In yet other embodiments, thegrain item can be maize, rice, wheat, barley, sorghum, millet, oat,triticale, rye, buckwheat, fonio or quinoa.

In some embodiments, the target to be treated by the present methods canbe a medium, a surface, a container, an equipment, or a system in ahealth care facility, e.g., a physical office or a hospital. Anysuitable concentration of peroxyformic acid can be used in the presentmethods. For example, the peroxyformic acid can be used at aconcentration from about 0.1 ppm, 0.5 ppm, or from about 10 ppm to about300 ppm, e.g., 10-15 ppm, 15-20 ppm, 20-25 ppm, or 25-30 ppm, 30-40 ppm,40-50 ppm, 50-60 ppm, 60-70 ppm, 70-80 ppm, 80-90 ppm, 90-100 ppm,100-150 ppm, 150-200 ppm, 200-250 ppm, or 250-300 ppm of peroxyformicacid.

The present methods can be used for treating a target that is at least aportion of a container, an equipment, a system or a facility forholding, processing, packaging, storing, transporting, preparing,cooking or serving the food item or the plant item. In some embodiments,the target is at least a portion of a container, an equipment, a systemor a facility for holding, processing, packaging, storing, transporting,preparing, cooking or serving a meat item, a fruit item, a vegetableitem, or a grain item. In other embodiments, the target is at least aportion of a container, an equipment, a system or a facility forholding, processing, packaging, storing, or transporting an animalcarcass. In still other embodiments, the target is at least a portion ofa container, an equipment, a system or a facility used in foodprocessing, food service or health care industry. In yet otherembodiments, the target is at least a portion of a fixed in-placeprocess facility. An exemplary fixed in-place process facility cancomprise a milk line dairy, a continuous brewing system, a pumpable foodsystem or a beverage processing line.

The present methods can be used for treating a target that is at least aportion of a solid surface or liquid media. In some embodiments, thesolid surface is an inanimate solid surface. The inanimate solid surfacecan be contaminated by a biological fluid, e.g., a biological fluidcomprising blood, other hazardous body fluid, or a mixture thereof. Inother embodiments, the solid surface can be a contaminated surface. Anexemplary contaminated surface can comprise the surface of food servicewares or equipment, or the surface of a fabric.

In an application of use for treating a surface, such as a fixedin-place process facility (e.g. brewing system), the treatmentbeneficially removes soils that are difficult to remove, as brewing beerand wine requires the fermentation of sugars derived from starch-basedmaterial e.g., malted barley or fruit juice, e.g., grapes. Fermentationuses yeast to turn the sugars in wort or juice to alcohol and carbondioxide. During fermentation, the wort becomes beer and the juicebecomes wine. Once the boiled wort is cooled and placed in a fermenter,yeast and/or bacteria is propagated in the wort and it is left toferment, which requires a week to months depending on the type of yeastor bacteria and style of the beer or wine. In addition to producingalcohol, fine particulate matter suspended in the wort settles duringfermentation. Once fermentation is complete, the yeast also settles,leaving the beer or wine clear, but the fermentation tanks soiled withdead yeast cells, proteins, hop resins, and/or grape skins. In aparticular embodiment of the invention, the method of cleaning may be aCIP technique. In another embodiment of the invention, the method ofcleaning may be directed at brewery surfaces.

The peroxyformic acid can be applied in any suitable manner. In someembodiments, the peroxyformic acid can be applied to a target by meansof a spray, a fog, or a foam, or by dipping all or part of the target ina composition comprising the peroxyformic acid. In some embodiments, theperoxyformic acid composition is applied to the target by means of aspray, a fog, or a foam. In other embodiments, the diluted peroxyformicacid is applied to the target by applying in the form of a thickened orgelled solution. In still other embodiments, all or part of the targetis dipped in the peroxyformic acid composition. The target and/or theperoxyformic acid composition can be subject to any suitable movement tohelp or facilitate the contact between the target and the peroxyformicacid composition. In some embodiments, the peroxyformic acid compositioncan be agitated. In other embodiments, the peroxyformic acid compositioncan be sprayed onto a target, e.g., an animal carcass, under suitablepressure and at a suitable temperature. For example, the peroxyformicacid composition can be sprayed onto an animal carcass at a pressure ofat least 50 psi at a temperature of up to about 60° C., resulting in acontact time of at least 30 seconds.

The present methods can comprise any suitable, additional steps. In someembodiments, the present methods can comprise a vacuum treatment step.In other embodiments, the present methods can comprise a step ofapplying an activated light source to the target, e.g., an animalcarcass.

The contacting step in the present methods can last for any suitableamount of time. In some embodiments, the contacting step can last for atleast about 30 seconds. For example, the contacting step can last for atleast about 30, 40, 50 seconds, 1 minute, 1-2 minutes, 2-3 minutes, 3-4minutes, 4-5 minutes, 5-6 minutes, 6-7 minutes, 7-8 minutes, 8-9minutes, or 9-10 minutes, 10-15 minutes, 15-20 minutes, 20-25 minutes,25-30 minutes, 30-40 minutes, 40-50 minutes, 50-60 minutes, 1-2 hours,2-3 hours, 3-4 hours, 4-5 hours, 5-6 hours, 6-7 hours, 7-8 hours, 8-9hours, or 9-10 hours, 16 hours, 1 day, 3 days, 1 week, or untildegradation or exhaustion of the chemistry. In an aspect, the contactingstep is preferably from about 30 seconds to about 4 hours.

The present methods can be used to reduce microbial population in and/oron the target or the treated target composition by any suitablemagnitude. In some embodiments, the present methods can be used toreduce microbial population in and/or on the target or the treatedtarget composition by at least one log₁₀, two log₁₀, three log₁₀, fourlog₁₀, five log₁₀, or more. In other embodiments, the level of amicroorganism, if present in and/or on the target or the treated targetcomposition, can be stabilized or reduced by the present methods. Forexample, at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% or moreof the microorganism, if present in and/or on the target or the treatedtarget composition, can be killed, destroyed, removed and/or inactivatedby the present methods.

In some embodiments, the antimicrobial efficacy of the composition usedin the present methods on the treated water source is comparable toantimicrobial effect of a water source that does not contain producedwater. In other embodiments, the treated water source reduces corrosioncaused by hydrogen peroxide and reduces microbial-induced corrosion, andthe composition used in the present methods does not substantiallyinterfere with a friction reducer, a viscosity enhancer, otherfunctional ingredients present in the treated water source, or acombination thereof.

The present methods can be used to reduce population of any suitablemicrobe(s) in and/or on the target or the treated target composition byany suitable magnitude. In some embodiments, the present methods can beused to reduce a prokaryotic microbial population, e.g., a bacterial oran archaeal population. In other embodiments, the present methods can beused to reduce an eukaryotic microbial population, e.g., a protozoal orfungal population. In still other embodiments, the present methods canbe used to reduce a viral population. Exemplary viral population cancomprise a population of a DNA virus, a RNA virus, and a reversetranscribing virus.

The present methods can be used to stabilize or reduce a microbialpopulation in and/or on the target or the treated target composition,wherein the target is a food item or a plant item and the contactingstep minimizes or does not induce an organoleptic effect in and/or onthe food item or a plant item. Typical organoleptic properties includethe aspects of food or other substances as experienced by the senses,including taste, sight, smell, and touch, in cases where dryness,moisture, and stale-fresh factors are to be considered. See e.g., JasperWomach, the Congressional Research Service document “Report forCongress: Agriculture: A Glossary of Term, Programs, and Laws, 2005Edition.” In some embodiments, organoleptic procedures are performed aspart of the meat and poultry inspections to detect signs of disease orcontamination. In other embodiments, organoleptic tests are conducted todetermine if package materials and components can transfer tastes andodors to the food or pharmaceutical products that they are packaged in.Shelf life studies often use taste, sight, and smell (in addition tofood chemistry and toxicology tests) to determine whether a food productis suitable for consumption. In still other embodiments, organoleptictests are conducted as part of the Hurdle technology. Typically, Hurdletechnology refers to an intelligent combination of hurdles which securesthe microbial safety and stability as well as the organoleptic andnutritional quality and the economic viability of food products. Seegenerally, Leistner L (1995) “In Gould G W (Ed.) New Methods of FoodPreservation, Springer, pp. 1-21; and Leistner I (2000) “InternationalJournal of Food Microbiology, 55:181-186.

The present methods can be conducted at any suitable temperature range.In some embodiments, the present methods can be conducted at atemperature ranging from about 0° C. to about 70° C., e.g., about 0°C.-1° C., 1° C.-2° C., 2° C.-3° C., 3° C.-4° C., 4° C.-5° C., 5° C.-10°C., 10° C.-15° C., 15° C.-20° C., 20° C.-25° C., 25° C.-30° C., 30°C.-35° C., 35° C.-40° C., 40° C.-45° C., 45° C.-50° C., 50° C.-55° C.,55° C.-60° C., 60° C.-65° C., or 65° C.-70° C. In other embodiments, thepresent methods can be conducted at a temperature at or lower than 0° C.

In some embodiments, the present methods can comprise adding aperoxidase or a catalase to further reduce the hydrogen peroxideconcentration in and/or on the target or the treated target composition.The peroxidase or catalase can be added in any suitable manner. In someembodiments, the peroxidase or catalase can be added to the target orthe treated target composition before a composition used in the presentmethods is provided to the target, e.g., a water source. In otherembodiments, the present compositions can be diluted into a suitableintermediate volume, and the peroxidase or catalase can be added to thediluted, intermediate volume. Thereafter, the diluted, intermediatevolume, which contains the peroxidase or catalase, can be added totarget, e.g., a water source. Any suitable peroxidase or catalase,including the ones described below, can be used in the present methods.

In some embodiments, the present methods can further comprise disposingof the treated water source or directing the treated water source into asubterranean environment, e.g., a subterranean environment thatcomprises a well in a gas and/or oil.

In some embodiments, the water source treated by the present methodsdoes not comprise reuse water, the treated water source comprises fromabout 10 ppm to about 20 ppm of peroxyformic acid, e.g., in situ formedperoxyformic acid, and from about 1 ppm to about 2 ppm of hydrogenperoxide and the treated water source does not comprise a frictionreducer and/or a rheology modifier.

In some embodiments, the water source treated by the present methods isa blended water source that comprises about 80 wt-% fresh water or pondwater and about 20 wt-% of reuse water, the treated water sourcecomprises from about 25 ppm to about 35 ppm of peroxyformic acid, e.g.,in situ formed peroxyformic acid, and from about 2 ppm to about 3 ppm ofhydrogen peroxide and catalase, the treated water source does notcomprise a friction reducer and/or a rheology modifier, and the treatedwater source is formed before reaching a blending tub.

In some embodiments, the water source treated by the present methods isa blended water source that comprises about 80 wt-% fresh water or pondwater and about 20 wt-% of reuse water, the treated water sourcecomprises from about 25 ppm to about 35 ppm of peroxyformic acid, e.g.,in situ formed peroxyformic acid, and from about 2 ppm to about 3 ppm ofhydrogen peroxide and catalase, the treated water source comprises afriction reducer and/or a rheology modifier, and the treated watersource is formed in a blending tub.

In some embodiments, the treated water source comprises from about 30ppm or less of peroxyformic acid, e.g., in situ formed peroxyformicacid, and about 0.5 ppm or less of the hydrogen peroxide, the treatedwater source comprises a friction reducer and/or a rheology modifier,and the treated water source is directed into or is at a subterraneanenvironment.

In some aspects, the methods disclosed for water treatment in oil andgas recovery provide effective antimicrobial efficacy withoutdeleterious interaction with functional agents, including for examplefriction reducers. In a further aspect, the methods for water treatmentprovide increased antimicrobial efficacy compared to the use of theantimicrobial peracids alone. In a still further aspect, the methods ofuse result in the disposal of cleaner water with low numbers ofmicroorganisms. In yet a further aspect of the methods of the invention,the reduction and/or elimination of H₂O₂ from the peracid compositionsminimizes the negative effects of the oxidant H₂O₂.

Use in Water Treatment

The peroxyformic acid compositions can be used for a variety ofindustrial applications, e.g., to reduce microbial or viral populationson a surface or object or in a body or stream of water. In some aspects,the invention includes methods of using the peroxyformic acidcompositions to prevent biological fouling in various industrialprocesses and industries, including oil and gas operations, to controlmicroorganism growth, eliminate microbial contamination, limit orprevent biological fouling in liquid systems, process waters or on thesurfaces of equipment that come in contact with such liquid systems. Asreferred to herein, microbial contamination can occur in variousindustrial liquid systems including, but not limited to, air-bornecontamination, water make-up, process leaks and improperly cleanedequipment. In another aspect, peroxyformic acid and/or catalasecompositions are used to control the growth of microorganisms in waterused in various oil and gas operations. In a further aspect, thecompositions are suitable for incorporating into fracturing fluids tocontrol or eliminate microorganisms.

As used herein for the methods of the invention, the peroxyformic acidcompositions can employ a variety of peroxyformic acid compositionshaving a low to substantially no hydrogen peroxide concentration. Theseperoxyformic acid compositions include peroxyformic acid compositionswith a catalase or peroxidase enzyme to reduce the hydrogen peroxide toperacid ratio and/or other reduced hydrogen peroxide peroxyformic acidcompositions disclosed herein. In a specific embodiment peroxyformicacid and catalase use solutions having reduced or substantially nohydrogen peroxide are introduced to a water source in need of treatment.

The methods by which the peroxyformic acid solutions are introduced intothe aqueous fluids according to the invention are not critical.Introduction of the peroxyformic acid compositions may be carried out ina continuous or intermittent manner and will depend on the type of waterbeing treated. In some embodiments, the peroxyformic acid compositionsare introduced into an aqueous fluid according to the methods disclosedin U.S. Patent Publication No. 2014/0096971, titled “New Method andArrangement for Feeding Chemicals into a Hydrofracturing Process and Oiland Gas Applications”, which is hereby incorporated by reference in itsentirety.

In an aspect, the peroxyformic acid solutions are added to waters inneed of treatment prior to the drilling and fracking steps in order torestrict the introduction of microbes into the reservoir and to preventthe microbes from having a negative effect on the integrity of thefluids. The treatment of source waters (e.g. pond, lake, municipal,etc.) and/or produced waters is particularly well suited for useaccording to the invention.

The treated waters according to the invention can be used for both slickwater fracturing (i.e. using frictions reducers) and/or gel fracturing(i.e. using viscosity enhancers), depending on the type of formationbeing fractured and the type of hydrocarbon expected to be produced. Useof a peroxyformic acid solution, including a catalase treatedperoxyformic acid composition use solution having low to substantiallyno hydrogen peroxide, is suitable for both slick water fracturing andgel fracturing.

In an aspect, pretreating the peroxyformic acid composition withcatalase substantially removes the hydrogen peroxide with minimal to noimpact on the fracturing fluids and the well itself. In an aspect, theperoxyformic acid composition pretreated with catalase allows theformation of gel suitable for gel fracturing, as opposed to untreatedperoxyformic acid composition solutions that do not allow a gel to formunder certain conditions. In a further aspect, the peroxyformic acidcomposition solutions are added to waters in need of treatment in thesubterranean well formations (e.g. introduced through a bore hole in asubterranean formation). These methods provide additional control withinthe well formation suitable for reducing microbial populations alreadypresent within the down-hole tubing in the well or within the reservoiritself.

In a still further aspect, the peroxyformic acid composition solutionsare added to waters in need of treatment before disposal. In such anaspect, flow back waters (e.g. post fracking) are treated to minimizemicrobial contaminations in the waters and to remove solids prior todisposal of the water into a subterranean well, reuse in a subsequentfracturing application or return of the water into local environmentalwater sources.

In an aspect, the water source in need of treatment may varysignificantly. For example, the water source may be a freshwater source(e.g. pond water), salt water or brine source, brackish water source,recycled water source, or the like. In an aspect, wherein offshore welldrilling operations are involved, seawater sources are often employed(e.g. saltwater or non-saltwater). Beneficially, the peroxyformic acidcompositions, with or without catalase, of the invention are suitablefor use with any types of water and provide effective antimicrobialefficiency with any of such water sources.

Large volumes of water are employed according to the invention asrequired in well fluid operations. As a result, in an aspect of theinvention, recycled water sources (e.g. produced waters) are oftenemployed to reduce the amount of a freshwater, pond water or seawatersource required. Recycled or produced water are understood to includenon-potable water sources. The use of such produced waters (incombination with freshwater, pond water or seawater) reduces certaineconomic and/or environmental constraints. In an aspect of theinvention, thousands to millions of gallons of water may be employed andthe combination of produced water with fresh water sources providessignificant economic and environmental advantages. In an aspect of theinvention, as much produced water as practical is employed. In anembodiment at least 1% produced water is employed, preferably at least5% produced water is employed, preferably at least 10% produced water isemployed, preferably at least 20% produced water is employed, or morepreferably more than 20% produced water is employed. In another aspect,up to 100% of produced water can be employed.

In an aspect of the invention, the method includes a pretreatment step,wherein the peroxyformic acid composition is treated with a catalaseenzyme to reduce the hydrogen peroxide concentration in a use solution.The pretreatment step occurs prior to combining the peracidantimicrobial composition and/or catalase to a water source in need oftreatment. In an aspect of the invention, the pretreatment may occurwithin a few minutes to hours before addition to a water source.

According to embodiments of the invention, a sufficient amount of theperoxyformic acid composition, with or without catalase, is added to theaqueous water source in need of treatment to provide the desiredperoxyformic acid concentration for antimicrobial efficacy. For example,a water source is dosed amounts of the peroxyformic acid and catalaseuse solution composition until a peroxyformic acid concentration withinthe water source is detected within the preferred concentration range(e.g. about 1 ppm to about 100 ppm peracid). In an aspect, it ispreferred to have a microbial count of less than about 100,000microbes/mL, more preferably less than about 10,000 microbes/mL, or morepreferably less than about 1,000 microbes/mL.

The methods of use as described herein can vary in the temperature andpH conditions associated with use of the aqueous treatment fluids. Forexample, the aqueous treatment fluids may be subjected to varyingambient temperatures according to the applications of use disclosedherein, including ranging from about 0° C. to about 130° C. in thecourse of the treatment operations. Preferably, the temperature range isbetween about 5° C. to about 100° C., more preferably between about 10°C. to about 80° C. However, as a majority of the antimicrobial activityof the compositions of the invention occurs over a short period of time,the exposure of the compositions to relatively high temperatures is nota substantial concern. In addition, the peracid composition aqueoustreatment fluids (i.e. use solutions) may be subjected to varying pHranges, such as from 1 to about 10.5. Preferably, the pH range is lessthan about 9, less than about 8.2 or 8 to ensure the effectiveantimicrobial efficacy of the peracid.

The antimicrobial compositions of the invention are fast-acting.However, the present methods require a certain minimal contact time ofthe compositions with the water in need of treatment for occurrence ofsufficient antimicrobial effect. The contact time can vary withconcentration of the use compositions, method of applying the usecompositions, temperature of the use compositions, pH of the usecompositions, amount of water to be treated, amount of soil orsubstrates in the water to be treated, or the like. The contact orexposure time can be at least about 15 seconds. In some embodiments, theexposure time is about 1 to 5 minutes. In other embodiments, theexposure time is at least about 10 minutes, 30 minutes, or 60 minutes.In other embodiments, the exposure time is a few minutes to hours. Thecontact time will further vary based upon the concentration of peracidin a use solution.

Beneficial Effects of the Methods of Use in Water Treatment

In an aspect, the methods of use provide an antimicrobial for use thatdoes not negatively impact the environment. Beneficially, thedegradation of the compositions of the invention provides a “green”alternative.

In a further aspect, the methods of use provide an antimicrobial for usethat does not negatively interfere with friction reducers, viscosityenhancers and/or other functional ingredients. In a further aspect, themethods of use do not negatively interfere with any additionalfunctional agents utilized in the water treatment methods, including forexample, corrosion inhibitors, descaling agents and the like. Thecompositions administered according to the invention provide extremelyeffective control of microorganisms without adversely affecting thefunctional properties of any additive polymers of an aqueous system. Inaddition, the peroxyformic acid compositions provide additional benefitsto a system, including for example, reducing corrosion within the systemdue to the decreased or substantially eliminated hydrogen peroxide froma treated composition. Beneficially, the non-deleterious effects of theperoxyformic acid compositions (with or without a catalase) on thevarious functional ingredients used in water treatment methods areachieved regardless of the make-up of the water source in need oftreatment.

In an additional aspect, the methods of use prevent the contamination ofsystems, such as well or reservoir souring. In further aspects, themethods of use prevent microbiologically-influenced corrosion of thesystems upon which it is employed.

In further aspects, the methods of use employ the antimicrobial and/orbleaching activity of the peroxyformic acid compositions. For example,the invention includes a method for reducing a microbial populationand/or a method for bleaching. These methods can operate on an article,surface, in a body or stream of water or a gas, or the like, bycontacting the article, surface, body, or stream with the compositions.Contacting can include any of numerous methods for applying thecompositions, including, but not limited to, providing the antimicrobialperoxyformic acid compositions in an aqueous use solution and immersingany articles, and/or providing to a water source in need of treatment.

The compositions are suitable for antimicrobial efficacy against a broadspectrum of microorganisms, providing broad spectrum bactericidal andfungistatic activity. For example, the peracid biocides of thisinvention provide broad spectrum activity against wide range ofdifferent types of microorganisms (including both aerobic and anaerobicmicroorganisms), including bacteria, yeasts, molds, fungi, algae, andother problematic microorganisms associated with oil- and gas-fieldoperations.

Exemplary microorganisms susceptible to the peracid compositions of theinvention include, gram positive bacteria (e.g., Staphylococcus aureus,Bacillus species (sp.) like Bacillus subtilis, Clostridia sp.), gramnegative bacteria (e.g., Escherichia coli, Pseudomonas sp., Klebsiellapneumoniae, Legionella pneumophila, Enterobacter sp., Serratia sp.,Desulfovibrio sp., and Desulfotomaculum sp.), yeasts (e.g.,Saccharomyces cerevisiae and Candida albicans), molds (e.g., Aspergillusniger, Cephalosporium acremonium, Penicillium notatum, and Aureobasidiumpullulans), filamentous fungi (e.g., Aspergillus niger and Cladosporiumresinae), algae (e.g., Chlorella vulgaris, Euglena gracilis, andSelenastrum capricornutum), and other analogous microorganisms andunicellular organisms (e.g., phytoplankton and protozoa). Otherexemplary microorganisms susceptible to the peracid compositions of theinvention include the exemplary microorganisms disclosed in U.S. patentapplication US 2010/0160449 A1, e.g., the sulfur- or sulfate-reducingbacteria, such as Desulfovibrio and Desulfotomaculum species.

Use in Other Treatments

Additional embodiments of the invention include water treatments forvarious industrial processes for treating liquid systems. As usedherein, “liquid system” refers to flood waters or an environment withinat least one artificial artifact, containing a substantial amount ofliquid that is capable of undergoing biological fouling. Liquid systemsinclude but are not limited to industrial liquid systems, industrialwater systems, liquid process streams, industrial liquid processstreams, industrial process water systems, process water applications,process waters, utility waters, water used in manufacturing, water usedin industrial services, aqueous liquid streams, liquid streamscontaining two or more liquid phases, and any combination thereof.

In a further aspect, the present methods can also be used to treat otherliquid systems where both the compositions' antimicrobial function andoxidant properties can be utilized. Aside from the microbial issuessurrounding waste water, waste water is often rich in malodorouscompounds of reduced sulfur, nitrogen or phosphorous. A strong oxidantsuch as the compositions disclosed herein converts these compoundsefficiently to their odor free derivatives e.g. the sulfates, phosphatesand amine oxides. These same properties are very useful in the pulp andpaper industry where the property of bleaching is also of great utility.

The present methods can be conducted at any suitable temperature. Insome embodiments, the present methods are conducted at a temperatureranging from about −2° C. to about 70° C., e.g., from about −2° C. toabout 5° C., from about 0° C. to about 4° C. or 5° C., from about 5° C.to about 10° C., from about 11° C. to about 20° C., from about 21° C. toabout 30° C., from about 31° C. to about 40° C., including at about 37°C., from about 41° C. to about 50° C., from about 51° C. to about 60°C., or from about 61° C. to about 70° C.

The present methods can be used in the methods, processes or proceduresdescribed and/or claimed in U.S. Pat. Nos. 5,200,189, 5,314,687 and5,718,910. In some embodiments, the present methods can be used ofsanitizing facilities or equipment comprises the steps of contacting thefacilities or equipment with the composition of the present invention ata temperature in the range of about 4° C. to about 60° C. Theperoxyformic acid composition is then circulated or left in contact withthe facilities or equipment for a time sufficient to sanitize (generallyat least 30 seconds) and the treated target composition is thereafterdrained or removed from the facilities or equipment.

As noted above, the present methods are useful in the cleaning orsanitizing of processing facilities or equipment in the food service,food processing or health care industries. Examples of processfacilities in which the present methods can be employed include a milkline dairy, a continuous brewing system, food processing lines such aspumpable food systems and beverage lines, etc. Food service wares canalso be disinfected with the present methods. The present methods arealso useful in sanitizing or disinfecting solid surfaces such as floors,counters, furniture, medical tools and equipment, etc., found in thehealth care industry. Such surfaces often become contaminated withliquid body spills such as blood, other hazardous body fluids ormixtures thereof.

Generally, the actual cleaning of the in-place system or other surface(i.e., removal of unwanted offal therein) can be accomplished with adifferent material such as a formulated detergent which is introducedwith heated water. After this cleaning step, the peroxyformic acidcomposition can be applied or introduced into the system at a usesolution concentration in unheated, ambient temperature water. In someembodiments, the peroxyformic acid composition is found to remain insolution in cold (e.g., 40° F./4° C.) water and heated (e.g., 140°F./60° C.) water. Although it is not normally necessary to heat theaqueous use solution of the peroxyformic acid composition, under somecircumstances heating may be desirable to further enhance itsantimicrobial activity.

In some embodiments, a method of sanitizing substantially fixed in-placeprocess facilities comprises the following steps. The peroxyformic acidcomposition of the present invention is introduced into the processfacilities at a temperature in the range of about 4° C. to about 60° C.After introduction of the use solution, the solution is circulatedthroughout the system for a time sufficient to sanitize the processfacilities (i.e., to kill undesirable microorganisms). After the systemhas been sanitized by means of the present composition, the usecomposition or solution is drained from the system. Upon completion ofthe sanitizing step, the system optionally may be rinsed with othermaterials such as potable water. The present composition is preferablycirculated through the process facilities for 10 minutes or less.

In other embodiments, the present peroxyformic acid composition may alsobe employed by dipping food processing equipment into the diluted (oruse) composition or solution of the present invention, soaking theequipment for a time sufficient to sanitize the equipment, and wiping ordraining excess solution off the equipment. The composition may befurther employed by spraying or wiping food processing surfaces with theuse solution, keeping the surfaces wet for a time sufficient to sanitizethe surfaces, and removing the excess composition or solution by wiping,draining vertically, vacuuming, etc.

In still other embodiments, the present peroxyformic acid compositionmay also be used in a method of sanitizing hard surfaces such asinstitutional type equipment, utensils, dishes, health care equipment ortools, and other hard surfaces. The present peroxyformic acidcomposition may also be employed in sanitizing clothing items or fabricwhich has become contaminated. The peroxyformic acid composition iscontacted with any of the above contaminated surfaces or items at usetemperatures in the range of about 4° C. to about 60° C. for a period oftime effective to sanitize, disinfect, or sterilize the surface or item.For example, the present composition can be injected into the wash orrinse water of a laundry machine and contacted with contaminated fabricfor a time sufficient to sanitize the fabric. Excess composition orsolution can then be removed by rinsing or centrifuging the fabric.

The present methods can be used in the methods, processes or proceduresdescribed and/or claimed in U.S. Pat. Nos. 6,165,483 and 6,238,685, totreat field or greenhouse grown plant tissue, seeds, fruits, and growingmedia and containers. The present peroxyformic acid composition canlower the natural, plant pathogen and human pathogenic microbial loadresulting in less waste to molding, spoilage, and destruction because ofpathogenic poisons.

In some embodiments, the present peroxyformic acid composition can beused to protect growing plant tissue from the undesirable effects ofmicrobial attack. The present peroxyformic acid composition can beapplied to growing plant tissues and can provide residual antimicrobialeffects after the plant has completed its growth cycle, fruit orvegetable material have been harvested and sent to market. The presentcomposition can be an effective treatment of living or growing planttissues including seeds, roots, tubers, seedlings, cuttings, rootingstock, growing plants, produce, fruits and vegetables, etc. Undercertain circumstances, a single peroxyacid material can be effective,however, in other circumstances, a mixed peroxy acid has substantiallyimproved and surprising properties.

In some embodiments, the composition used in the present methods alsomay contain a hydrotrope for the purpose of increasing the aqueoussolubility of various slightly soluble organic compounds. The preferredembodiment of the composition utilizes a hydrotrope chosen from thegroup of n-octanesulfonate, a xylene sulfonate, a naphthalene sulfonate(naphthenic acid), ethylhexyl sulfate, lauryl sulfate, an amine oxide,or a mixture thereof.

In some embodiments, the composition used in the present methods mayalso contain a chelating agent for the purpose of removing ions fromsolution. The preferred embodiment of the invention uses1-hydroxyethylidene-1,1-diphosphonic acid.

The present methods can be used in the methods, processes or proceduresdescribed and/or claimed in U.S. Pat. Nos. 6,010,729, 6,103,286,6,545,047 and 8,030,351 for sanitizing animal carcasses.

In some embodiments, the compositions of the present invention can beused in a method of treating animal carcasses to obtain a reduction byat least one log₁₀ in surface microbial population which method includesthe step of treating said carcass with a composition of the presentinvention comprising an effective antimicrobial amount comprising atleast 2 parts per million (ppm, parts by weight per each one millionparts) of one or more peroxycarboxylic acids having up to 12 carbonatoms, an effective antimicrobial amount comprising at least 20 ppm ofone or more carboxylic acids having up to 18 carbon atoms, and the firstand second stabilizing agents described above, to reduce the microbialpopulation.

In yet other embodiments, the present invention is directed to a methodof treating an animal carcass to reduce a microbial population inresulting cut meat, the method comprising the steps of spraying anaqueous antimicrobial treatment composition onto said carcass at apressure of at least 50 psi at a temperature of up to about 60° C.resulting in a contact time of at least 30 seconds, the antimicrobialcomposition comprising an effective antimicrobial amount comprisingleast 2 ppm of one or more carboxylic acid, peroxycarboxylic acid ormixtures thereof, and the first and second stabilizing agents describedabove; and achieving at least a one log₁₀ reduction in the microbialpopulation.

In yet other embodiments, the present invention is directed to a methodof treating an animal carcass to reduce a microbial population inresulting cut meat, the method comprising the steps of placing theanimal carcass in a chamber at atmospheric pressure; filling the chamberwith condensing steam comprising an antimicrobial composition, e.g., adiluted composition of the present invention, for a short duration; andquickly venting and cooling the chamber to prevent browning of the meatcarcass; wherein the duration of the steam thermal process may be fromabout 5 seconds to about 30 seconds and the chamber temperature mayreach from about 50° C. to about 93° C.

The antimicrobial composition can be applied in various ways to obtainintimate contact with each potential place of microbial contamination.For example, it can be sprayed on the carcasses, or the carcasses can beimmersed in the composition. Additional methods include applying afoamed composition and a thickened or gelled composition. Vacuum and orlight treatments can be included, if desired, with the application ofthe antimicrobial composition. Thermal treatment can also be applied,either pre-, concurrent with or post application of the antimicrobialcomposition.

One preferred spray method for treating carcasses with dilutedcompositions of the present invention involves spraying the carcass withan aqueous spray at a temperature less than about 60° C. at a pressureof about 50 to 500 psi gauge wherein the spray comprises an effectiveantimicrobial amount of a carboxylic acid, an effective antimicrobialamount of a peroxycarboxylic acid or mixtures thereof, and the first andsecond stabilizing agents described above. These sprays can also containan effective portion of a peroxy compound such as hydrogen peroxide andother ingredients such as sequestering agents, etc. The high pressurespray action of the aqueous treatment can remove microbial populationsby combining the mechanical action of the spray with the chemical actionof the antimicrobial materials to result in an improved reduction ofsuch populations on the surface of the carcass.

All pressures are psig (or psi gauge). In some embodiments,differentiation of antimicrobial “-cidal” or “-static” activity, thedefinitions which describe the degree of efficacy, and the officiallaboratory protocols for measuring this efficacy are importantconsiderations for understanding the relevance of antimicrobial agentsin compositions. Antimicrobial compositions may affect two kinds ofmicrobial cell damages. The first is a truly lethal, irreversible actionresulting in complete microbial cell destruction or incapacitation. Thesecond type of cell damage is reversible, such that if the organism isrendered free of the agent, it can again multiply. The former is termedbacteriocidal and the latter, bacteriostatic. A sanitizer and adisinfectant are, by definition, agents which provide antibacterial orbacteriocidal activity and may achieve at least a five-fold reduction(i.e., a five log₁₀ reduction) in microbial populations after a 30second contact time (see AOAC method 960.09).

The present methods can be used in the methods, processes or proceduresdescribed and/or claimed in U.S. Pat. Nos. 8,017,409 and 8,236,573. Insome embodiments, the present methods may be used for a variety ofdomestic or industrial applications, e.g., to reduce microbial or viralpopulations on a surface or object or in a body or stream of water. Theperoxyformic acid compositions of the present invention may be appliedin a variety of areas including kitchens, bathrooms, factories,hospitals, dental offices and food plants, and may be applied to avariety of hard or soft surfaces having smooth, irregular or poroustopography. Suitable hard surfaces include, for example, architecturalsurfaces (e.g., floors, walls, windows, sinks, tables, counters andsigns); eating utensils; hard-surface medical or surgical instrumentsand devices; and hard-surface packaging. Such hard surfaces may be madefrom a variety of materials including, for example, ceramic, metal,glass, wood or hard plastic. Suitable soft surfaces include, for examplepaper; filter media, hospital and surgical linens and garments;soft-surface medical or surgical instruments and devices; andsoft-surface packaging. Such soft surfaces may be made from a variety ofmaterials including, for example, paper, fiber, woven or non-wovenfabric, soft plastics and elastomers. The diluted (or use) compositionsmay also be applied to soft surfaces such as food and skin (e.g., ahand). The diluted (or use) compositions may be employed as a foaming ornon-foaming environmental sanitizer or disinfectant.

In other embodiments, the peroxyformic acid compositions of the presentinvention may be included in products such as sterilants, sanitizers,disinfectants, preservatives, deodorizers, antiseptics, fungicides,germicides, sporicides, virucides, detergents, bleaches, hard surfacecleaners, hand soaps, waterless hand sanitizers, and pre- orpost-surgical scrubs.

In still other embodiments, the peroxyformic acid compositions of thepresent invention may also be used in veterinary products such asmammalian skin treatments or in products for sanitizing or disinfectinganimal enclosures, pens, watering stations, and veterinary treatmentareas such as inspection tables and operation rooms. The peroxyformicacid compositions may be employed in an antimicrobial foot bath forlivestock or people.

In yet other embodiments, the present methods may be employed forreducing the population of pathogenic microorganisms, such as pathogensof humans, animals, and the like. Exemplary pathogenic microorganismsinclude fungi, molds, bacteria, spores, and viruses, for example, S.aureus, E. coli, Streptococci, Legionella, Pseudomonas aeruginosa,mycobacteria, tuberculosis, phages, or the like. Such pathogens maycause a variety of diseases and disorders, including Mastitis or othermammalian milking diseases, tuberculosis, and the like. The presentmethods may be used to reduce the population of microorganisms on skinor other external or mucosal surfaces of an animal. In addition, thepresent methods may be used to kill pathogenic microorganisms thatspread through transfer by water, air, or a surface substrate. In someapplications, the compositions of the present invention need only beapplied to the skin, other external or mucosal surfaces of an animalwater, air, or surface.

In yet other embodiments, the present methods may also be used on foodsand plant species to reduce surface microbial populations; used atmanufacturing or processing sites handling such foods and plant species;or used to treat process waters around such sites. For example, thepresent methods may be used on food transport lines (e.g., as beltsprays); boot and hand-wash dip-pans; food storage facilities;anti-spoilage air circulation systems; refrigeration and coolerequipment; beverage chillers and warmers, blanchers, cutting boards,third sink areas, and meat chillers or scalding devices. The presentmethods may be used to treat transport waters such as those found influmes, pipe transports, cutters, slicers, blanchers, retort systems,washers, and the like. Particular foodstuffs that may be treated withthe present methods include eggs, meats, seeds, leaves, fruits andvegetables. Particular plant surfaces include both harvested and growingleaves, roots, seeds, skins or shells, stems, stalks, tubers, corms,fruit, and the like. The present methods may also be used to treatanimal carcasses to reduce both pathogenic and non-pathogenic microbiallevels.

In yet other embodiments, the present methods may be useful in thecleaning or sanitizing of containers, processing facilities, orequipment in the food service or food processing industries. The presentmethods may be used on food packaging materials and equipment, includingfor cold or hot aseptic packaging. Examples of process facilities inwhich the present methods may be employed include a milk line dairy, acontinuous brewing system, food processing lines such as pumpable foodsystems and beverage lines, etc. Food service wares may be disinfectedwith the present methods. For example, the present methods may also beused on or in ware wash machines, dishware, bottle washers, bottlechillers, warmers, third sink washers, cutting areas (e.g., waterknives, slicers, cutters and saws) and egg washers. Particular treatablesurfaces include packaging such as cartons, bottles, films and resins;dish ware such as glasses, plates, utensils, pots and pans; ware washmachines; exposed food preparation area surfaces such as sinks,counters, tables, floors and walls; processing equipment such as tanks,vats, lines, pumps and hoses (e.g., dairy processing equipment forprocessing milk, cheese, ice cream and other dairy products); andtransportation vehicles. Containers include glass bottles, PVC orpolyolefin film sacks, cans, polyester, PEN or PET bottles of variousvolumes (100 ml to 2 liter, etc.), one gallon milk containers, paperboard juice or milk containers, etc.

In yet other embodiments, the present methods may also be used on or inother industrial equipment and in other industrial process streams suchas heaters, cooling towers, boilers, retort waters, rinse waters,aseptic packaging wash waters, and the like. The present methods may beused to treat microbes and odors in recreational waters such as inpools, spas, recreational flumes and water slides, fountains, and thelike.

In yet other embodiments, a filter containing the peroxyformic acidcompositions of the present invention may be used to reduce thepopulation of microorganisms in air and liquids. Such a filter may beused to remove water and air-born pathogens such as Legionella.

In yet other embodiments, the present methods may be employed forreducing the population of microbes, fruit flies, or other insect larvaon a drain or other surface.

In yet other embodiments, the present methods may also be employed bydipping food processing equipment into the peroxyformic acid compositionor solution of the present invention, soaking the equipment for a timesufficient to sanitize the equipment, and wiping or draining excesscomposition or solution off the equipment. The present methods may befurther employed by spraying or wiping food processing surfaces with theperoxyformic acid composition or solution, keeping the surfaces wet fora time sufficient to sanitize the surfaces, and removing excesscomposition or solution by wiping, draining vertically, vacuuming, etc.

In yet other embodiments, the present methods may also be used forsanitizing hard surfaces such as institutional type equipment, utensils,dishes, health care equipment or tools, and other hard surfaces. Thepresent methods may also be employed in sanitizing clothing items orfabrics which have become contaminated. The peroxyformic acidcompositions of the present invention can be contacted with anycontaminated surfaces or items at use temperatures in the range of about4° C. to 60° C., for a period of time effective to sanitize, disinfect,or sterilize the surface or item. For example, the peroxyformic acidcompositions may be injected into the wash or rinse water of a laundrymachine and contacted with contaminated fabric for a time sufficient tosanitize the fabric. Excess composition may be removed by rinsing orcentrifuging the fabric.

In yet other embodiments, the peroxyformic acid compositions of thepresent invention may be applied to microbes or to soiled or cleanedsurfaces using a variety of methods. These methods may operate on anobject, surface, in a body or stream of water or a gas, or the like, bycontacting the object, surface, body, or stream with the diluted (oruse) composition. Contacting may include any of numerous methods forapplying a composition, such as spraying the composition, immersing theobject in the composition, foam or gel treating the object with thecomposition, or a combination thereof.

In yet other embodiments, the peroxyformic acid compositions of thepresent invention may be employed for bleaching pulp. The compositionsmay be employed for waste treatment. Such a composition may includeadded bleaching agent.

In yet other embodiments, other hard surface cleaning applications forthe peroxyformic acid compositions of the present invention includeclean-in-place systems (CIP), clean-out-of-place systems (COP),washer-decontaminators, sterilizers, textile laundry machines, ultra andnano-filtration systems and indoor air filters. COP systems may includereadily accessible systems including wash tanks, soaking vessels, mopbuckets, holding tanks, scrub sinks, vehicle parts washers,non-continuous batch washers and systems, and the like.

The concentrations of peroxyformic acid and/or hydrogen peroxide in theperoxyformic acid compositions of the present invention can be monitoredin any suitable manner. In some embodiments, the concentrations ofperoxyformic acid and/or hydrogen peroxide in the peroxyformic acidand/or hydrogen peroxide compositions can be monitored using a kineticassay procedure, e.g., the exemplary procedure disclosed in U.S. Pat.Nos. 8,017,409 and 8,236,573. This can be accomplished by exploiting thedifference in reaction rates between peroxyformic acid and hydrogenperoxide when using, for example, a buffered iodide reagent todifferentiate peroxyformic acid and hydrogen peroxide concentrationswhen both these analyte compounds are present in the use composition.The monitor may also determine the concentrations of peroxyformic acidand/or hydrogen peroxide in the presence of other additionalingredients, such as acidulants, one or more stabilizing agents,nonionic surfactants, semi-polar nonionic surfactants, anionicsurfactants, amphoteric or ampholytic surfactants, adjuvants, solvents,additional antimicrobial agents or other ingredients which may bepresent in the use composition.

Methods of Cleaning a Food Process Surface

As noted above, the present methods are useful in the cleaning orsanitizing of processing facilities or equipment in the food service,food processing or health care industries. Examples of processfacilities in which the present methods can be employed include a milkline dairy, a continuous brewing system, food processing lines such aspumpable food systems and beverage lines, etc. Food service wares canalso be disinfected with the present methods. The present methods arealso useful in sanitizing or disinfecting solid surfaces such as floors,counters, furniture, medical tools and equipment, etc., found in thehealth care industry. Such surfaces often become contaminated withliquid body spills such as blood, other hazardous body fluids ormixtures thereof.

Brewery soils are a type of soil that is particularly difficult toremove from a surface. Brewing beer requires the fermentation of sugarsderived from starch-based material. Fermentation uses yeast to turn thesugars in wort to alcohol and carbon dioxide. During fermentation, thewort becomes beer. Once the boiled wort is cooled and in a fermenter,yeast is propagated in the wort and it is left to ferment, whichrequires a week to months depending on the type of yeast and strength ofthe beer. In addition to producing alcohol, fine particulate mattersuspended in the wort settles during fermentation. Once fermentation iscomplete, the yeast also settles, leaving the beer clear, but thefermentation tanks soiled. Often during the fermentation process incommercial brewing, the fermentation tanks develop a ring of soil whichis particularly difficult to remove. Traditional CIP methods of cleaningthese tanks do not always remove this soil. Thus, brewers often resortto climbing inside of the tanks and manually scrubbing them to removethe soil. Accordingly there is need for improved methods and chemistriesfor removing these types of soils that are not easily removed usingconventional cleaning techniques.

Brewery Surface CIP Single Use Technique

According to an embodiment of the invention, the method of cleaning maybe used in a brewery surface CIP technique, including under an enrichedCO₂ atmosphere. In a further embodiment, the CIP technique may employsingle use equipment. The method can be performed at a temperaturebetween about 5° C. and about 100° C. In another embodiment of theinvention, the method can be performed at a temperature between about25° C. and about 60° C. In a further embodiment of the invention, themethod can be performed at a temperature between about 35° C. and about50° C.

The peroxyformic acid composition will be contacted with the brewerysurface CIP equipment as a use solution. The contacting can be performedin any suitable way. In an embodiment employing single use equipment,the method of cleaning does not return the use solution to a supply tankor recirculate it in a closed loop. Rather the use solution, remains inthe CIP equipment during the wash cycle. In a particular embodiment,optimal cleaning may occur when the use solution has an alkaline pH,e.g., above pH 8 (and accordingly use of an alkalinity source may beemployed). In a further aspect, the pH of the use solution may bemonitored by any known method of monitoring pH, including for example abuilt-in pH meter. In a particular embodiment of the invention, the pHand/or conductivity of the use solution may be adjusted by adding analkalinity source. In other embodiments of the invention, the pH and/orconductivity may not be monitored and adjusted.

Brewery Surface CIP Closed Loop Technique

According to an embodiment of the invention the method of cleaning maybe used in a brewery surface CIP closed loop technique, including underan enriched CO₂ atmosphere. The method can be performed at a temperaturebetween about 5° C. and about 100° C. In another embodiment of theinvention, the method can be performed at a temperature between about25° C. and about 60° C. In a further embodiment of the invention, themethod can be performed at a temperature between about 35° C. and about50° C.

In an embodiment employing closed loop equipment, the method of cleaningcan recirculate the use solution through the brewery surface beingcleaned. Thus, in a particular embodiment the recirculation of the usesolution can be performed in any suitable method of recirculating theuse solution. Such methods are well known and understood by those ofskill in the art. An example, includes, but is not limited to, using aclosed loop that recirculates the use solution through a built-in spraynozzle.

In a particular embodiment, optimal cleaning may occur when the usesolution has an alkaline pH, e.g., pH equal to and greater than 8. In aparticular embodiment of the invention, a secondary alkalinity sourcemay be added to the use solution. In a further aspect of the invention,the pH of the use solution may be monitored by any known method ofmonitoring pH, including for example a built-in pH meter. In aparticular embodiment of the invention, the pH of the use solution maybe adjusted by adding an alkalinity source. In an aspect of theinvention adding an alkalinity source may comprise recirculating the usesolution, recirculating the use solution with another alkalinity source,or simply adding another alkalinity source. In other embodiments of theinvention, the pH may not be monitored and adjusted.

In still a further aspect of the invention, the conductivity of the usesolution may be monitored by any known method of monitoringconductivity, including for example a built-in conductivity meter. In aparticular embodiment of the invention, the conductivity of the usesolution may be adjusted by adding a secondary alkalinity source. Inother embodiments of the invention, the conductivity may not bemonitored and adjusted.

According to an embodiment of the invention, a food process surface iscontacted by a cleaning composition. The cleaning composition may be ina concentrate or a diluted form generated according to the invention.Contacting can include any of numerous methods known by those of skillin the art for applying a compound or composition of the invention, suchas spraying, immersing the food process surface in the cleaningcomposition or use solution, dispensing the cleaning composition over asurface in granular or particulate form, simply pouring the cleaningcomposition or a use solution onto or into the food process surface,rinsing the food processing surface with a use solution, or acombination thereof.

Low Temperature Cleaning Applications

In other applications, lower temperatures can be employed for effectivesoil removal employing the peroxyformic acid compositions. In someaspects, the methods of the present invention provide for effective soilremoval without the necessity of high temperatures, i.e., above 60° C.Beneficially, the methods of the present invention do not require thesurface to be cleaned to be preheated. In some aspects, the methods ofthe present invention are more effective at lower temperatures than athigher temperatures, contrary to conventional CIP methods of cleaning.

In some aspects, the cleaning employing the peroxyformic acidcomposition occur at a temperature of about 2° C. to about 50° C. Insome embodiments, the methods of the present invention provide effectivesoil removal at ambient or room temperature, i.e., about 18° C. to about23° C. All values and ranges between these values and ranges are to beencompassed by the methods of the present invention. Beneficially, theability to clean at reduced temperatures results in energy and costsavings compared to traditional cleaning techniques that requireincreased temperatures. Further, the present invention provides foreffective soil removal on surfaces that cannot withstand hightemperatures.

EXAMPLES

The following examples are included for illustrative purposes only andare not intended to limit the scope of the invention.

Equilibrium peroxide is a required reagent and reaction product outcomeof all stable peroxy acid systems. In many applications, thisconcentration of peroxide can be a disadvantage for both concentrate anduse dilution outcome for use due to shipping or downstream treatmentprocess complications.

Removal of use dilution peroxide can be achieved with various waysincluding scrubbing the use concentration with enzymatic or halogenbased chemistries. In these cases, cost and time are an issue foreffective peroxide removal. Enzymatic peroxide removal is especiallyunviable in this environment because of high cost and instabilitiesassociated with the reaction conditions for the enzyme. Therefore thereis a need for a process of preparing a rapid release of oxygen whilemaintaining a pseudo stable concentrate after 24 hours.

One exemplary reagent is formic acid which leverages a unique rate offormation in combination with equilibrium peracid systems. In exemplaryembodiments, formic acid can act in two ways. First, use of formic acidin combination with an equilibrium peracid system can lead to rapidreduction of peroxide from the equilibrium formulation without gasrelease or exothermic reaction. Second, during consumption of peroxide,formic acid can form a semi-stable peracid with enhanced antimicrobial,oxidation, and bleaching performance.

In exemplary embodiments, performic acid can be used as an alternativeway to treat water in oil and gas industry that has the same or betterperformance as peracetic acid systems, but reduce or minimize oxygenrelated corrosion issues. Performic acid provides for significantadvantages in that it can be formulated at a high or higher ratio ofperacid to peroxide; it does not generate oxygen, and has significantlyreduced corrosion rates as compared to peracetic acid. Performic acidalso exhibits a better biocidal activity and reduces risks associatedwith microbial induced corrosion. These advantages make performic acid agood or an ideal choice for use in both on shore and offshore oil and/orgas exploration, production and completions. In addition, a very lowperoxide in the formulations containing a high or higher ratio ofperacid to peroxide increases the compatibilities with sensitivechemistries in unconventional oil and gas production (like Frac Gelapplications). The ability to oxidize iron sulfide and H₂S and theantimicrobial properties provide performic acid for a unique advantagefor the use in the oil and gas industry.

Example 1. Addition of Formic Acid to Peracetic Acid/Hydrogen Peroxideand Peroctanoic/Hydrogen Peroxide Systems. Addition of Formic Acid to aPeracetic Acid/Hydrogen Peroxide System

In this example, formic acid was added to a peracetic acid/hydrogenperoxide system to form a composition that contains performic acid.Formic acid was added to a final ratio of 20:80 formic acid: peraceticacid formulation (17.2% POAA, 3.6% H₂O₂). As shown in Table 1 below andin FIG. 1, addition of formic acid to the peracetic acid/hydrogenperoxide system increases total peracid concentration while decreasinghydrogen peroxide concentration.

TABLE 1 Addition of formic acid to a peracetic acid/hydrogen peroxidesystem peracetic acid formulation + formic acid time total peracid/(min) % total peracid % H₂O₂ H₂O₂ 0 13.8(calculated 2.9(calculatedvalue) value) 2 14.9 2.5 5.9 3 16.5 2.6 6.4 5 16.5 2.5 6.5 10 16.8 2.56.9 15 17.5 1.9 9.3 20 17.0 1.7 10.2 50 18.4 1.23 14.4 105 20.6 0.5 42.9290 19.8 0.7 30.5 400 18.3 0.6 31.0 1680 13.8 0.2 58.9 2760 13.3 0.263.5Addition of Formic Acid to a Peroctanoic Formulation (Octave FS)

In this example, formic acid was added to a peroctanoic acid/hydrogenperoxide system to form a composition that contains performic acid.Table 2 below shows addition of formic acid to a commercially-availableperoctanoic formulation (POOA) at different ratios.

TABLE 2 Addition of formic acid to a peroctanoic formulation (POOA,contains 0.5% POOA and 6.8% H₂O₂) at different ratios 0% 4% 8% 16% 32%POOA (mL) 5.0 5.0 5.0 5.0 5.0 Water (in mL) 5.0 4.6 4.2 3.4 1.8 Formicacid in mL) 0.4 0.8 1.6 3.2 Total (in mL) 10.0 10.0 10.0 10.0 10.0

Table 3 below lists the amount of total peracids formed (mixture ofperoctanoic and performic acids) in formulations containing varyingamounts of formic acid (0 to 32%). Table 4 below shows total peracidsand corresponding H₂O₂ concentration in formulations containingdifferent ratios of formic acid (0 to 32%) in 50% POOA (0.25% POOA, 3.4%H₂O₂) after 1690 min incubation at 22° C.

TABLE 3 The amount of total peracids formed in formulations containingvarying amounts of formic acid 32% 16% 8% 4% 0% Time Formic FormicFormic Formic Formic (min.) acid acid acid acid acid 20 1.9 0.7 0.4 0.280 2.0 0.7 0.3 0.3 155 2.5 1.0 0.5 0.3 255 1.9 0.8 0.4 0.3 0.1 1330 1.60.8 0.4 0.3 0.1

TABLE 4 Total peracids and corresponding H₂O₂ concentration informulations containing different ratios of formic acid in 50% POOAafter 1690 min incubation at 22° C. 32% 16% 8% 4% 0% PFA + POOA (in %)2.0 1.3 0.8 0.5 0.2 Peroxide (in %) 1.1 2.0 2.2 2.5 3.0

Example 2. Addition of 1:1 Ratio Formic Acid to a Peracid System.Addition of Formic Acid to a Peracetic Acid/Hydrogen Peroxide System

In this example, formic acid was added to a peracetic acid/hydrogenperoxide system to form a composition that contains performic acid. Asshown in Table 5 below and in FIG. 2, addition of 1:1 ratio formic acidto a peracid system (20.68% POAA, 3.43% H₂O₂) results in shift towardsvery low peroxide concentrations the composition of which is stable evenafter 5 days of mixing.

TABLE 5 Reduction in the concentration of peroxide in a peraceticacid/hydrogen peroxide system with formic acid Time (min) Wt (g) EP1(ml)EP2(ml) % (as POAA) % H₂O₂ 0 10.3 1.7 1 0.2970 8.6 1.8 11.0 1.0 110.3500 10.3 1.4 11.2 0.7 21 0.264 9.1 0.2 13.1 0.1 35 0.3095 9.8 0.712.0 0.4 80 0.2788 8.9 0.0 12.1 0.0 165 0.2138 7.6 0.0 13.5 0.0 3000.2150 6.3 0.0 11.1 0.0 1320 0.2925 9.2 0.0 11.9 0.0 1485 0.2324 7.0 0.111.4 0.1 7500 0.2050 5.5 0.2 10.2 0.2Addition of Formic Acid to a Peroctanoic Formulation

In this example, formic acid was added to a peroctanoic acid/hydrogenperoxide system to form a composition that contains performic acid. Asshown in Table 6 below and in FIG. 3, addition of 1:1 ratio formic acidto a peroctanoic acid/peroxide system (0.75% POOA, 7.45% H₂O₂) resultsin reduction in the concentration of hydrogen peroxide.

TABLE 6 Reduction in the concentration of hydrogen peroxide in aperoctanoic acid/hydrogen peroxide system % Peracid Time(min.) Wt (g)EP1(ml) EP2(ml) (as POOA) % H₂O₂ 0 0.4 3.7 1 0.2606 1.0 3.5 1.2 2.2 100.2144 2.7 1.2 4. 1.0 21 0.2885 4.1 1.2 4.6 0.7 35 0.3906 6.1 1.2 5.00.5 75 0.2179 3.4 0.6 5.0 0.5 170 0.3168 4.1 0.9 4.1 0.5 300 0.2344 3.10.6 4.2 0.4 1345 0.2325 2.7 0.4 3.7 0.3 1535 0.2300 2.3 0.4 3.2 0.3 75000.2451 1.4 0.6 1.8 0.4

Example 3. Influence of Hydrogen Peroxide on the Stability of Peracid inTest Systems

In formulations containing hydrogen peroxide present at equilibriumconcentrations, addition of formic acid reduces total peroxideconcentration in the system. This increases the stability andpersistence of peracetic acid in the system. Experiments were performedin a 20:80 mixture of produced water and tap water to mimic fieldconditions. As shown in Table 7 below, in formulations containing 10%peroxide, peracetic acid is completely consumed in 50 minutes comparedto 15% of the initial hydrogen peroxide concentration (at 1080 minutes)in formulations containing 3.5% peroxide. In formulations where theaddition of formic acid reduces total hydrogen peroxide to lowerconcentrations, the stability of peracid is greater with 34% of thetotal peracid added stable even after 1060 minutes.

TABLE 7 Influence of hydrogen peroxide on the stability of peracid intest systems POAA with 3.5% peroxide 10% peroxide 0% peroxide (POAA toH₂O₂ ratio) (POAA to H₂O₂ ratio) Normalized Normalized Normalized TimeResidual Time Residual Time Residual (min) POAA % (min) POAA % (min)POAA % 0 100.0 0 100.0 0 100.0 1 91.0 5 59.4 1 77.9 5 59.4 10.5 38.4 533.2 9 50.0 15 33.9 10 23.0 35 31.1 60 21.2 50 0.0 1060 34.9 1080 15.6

Example 4. Synergistic Antimicrobial Properties

Performic acid generated in a non-equilibrium peracid formulation havebeen found to be synergistic in kill performance when produced on sitewhen combined with C₁ to C₂₂ fatty acids and other peroxyacid systems.Synergy examples range from pH 0 to 12 at varied concentrations.Synergistic activity is defined as a technical effect that exceeds theaddition of the cumulative performance of the materials in formulation.As shown in Table 8 below, performic acid has shown synergistic killperformance with POOA, PSOA and POA when mixed on-site when peroxideconcentrations are in non-equilibrium states.

As referred to in Table 8 the following commercially-available testsubstances were employed: POAA (15% POAA, 10% H₂O₂), PAA 1 (21%peracetic, 3.5% H₂O₂), POOA (0.5% POOA, 6.8% H₂O₂).

TABLE 8 Synergistic kill performance of performic acid with POOA, PSOAand POA Test Exposure Log Water sample substance Concentration timereduction 80% tap water POOA 15 ppm POOA 5 min 2.02 20% produced POOA 30ppm POOA 5 min 4.18 water POOA 100 + 15 ppm POOA + 5 min 3.91 formicacid 5 ppm PFA PAA 1 15 ppm PAA 5 min 2.02 PAA 1 30 ppm PAA 5 min 3.04PAA 1 + 15 ppm PAA + 5 min 2.51 formic acid 1 ppm PFA POOA 5 ppm POOA 5min 0.15 POOA 2.5 ppm POOA 5 min 0.17 POOA + 2.5 ppm POOA + 5 min 5.73formic acid 7 ppm PFA Performic 2 ppm PFA 5 min 3.01 acid Performic 8.5ppm PFA 5 min 5.69 acid Performic 10 ppm PFA 5 min 5.28 acid

Example 5. Exemplary Methods of Generating Performic Acid

Although not exhaustive, the following exemplary methods can be utilizedfor forming and enhancing the rate of formation rates of the pseudostable reaction mixtures.

Use of Mineral Acids to Accelerate Formation of Performic Acid

As shown in FIG. 4, soluble mineral acids can be added to accelerateformation of performic acid. This can be used to compensate for theaddition of a formic acid salt mixture to reach a non-equilibriumformation.

Use of Acid Exchange Resin System for Forming Performic Acid

Addition of mineral acids alters the pH of the non-equilibrium mixture.Therefore for downstream process applications that are pH sensitive,acid exchange resin systems can be used and exhibit effectivenesssimilar to that of acid catalysts to accelerate the formation ofperformic acid. As shown in Table 9 below and FIG. 5, the rate offormation of peracetic acid is increased in the presence of an acidexchange resin system compared to that without using an acid exchangeresin. A commercially-available sulfonic acid exchange resin wasemployed (Dowex M-31) for the examples.

TABLE 9 The rate of formation of performic acid in the presence andabsence of an acid exchange resin system with Dowex without Dowex TimeM-31 M-31 (min) PFA ppm PFA ppm 0 400.0 200.0 6 1670.0 200.0 15 4030.0350.0 25 6260.0 500.0 35 11250.0 780.0 48 13470.0 1010.0 74 14800.01600.0 150 26600.0 3300.0 270 33700.0 6520.0 330 43000.0 5930.0Generation of Performic Acid from Solids

Performic acid and mixed performic acids can be generated by theaddition of a sodium salt of formate with a stabilized peroxide product.The kinetics of formation is limited by the solubility of sodium formatein solution. This method of peracid generation is also possible withC₁-C₂₂ peracid compositions. Table 10 below illustrates examples of thegeneration of performic acid by the addition of sodium formate to 10%weight/volume in formulations containing peroctanoic and peracetic acid.

TABLE 10 Exemplary generation of performic acid from sodium formate POOA(0.5% POOA, 6.8% POAA (15% POAA, 10% PAA 1 (21% peracetic, H₂O₂) H₂O₂)3.5% H₂O₂) Time % as % Time % as % Time % as % (min) POAA H₂O₂ (min)POAA H₂O₂ (min) POAA H₂O₂ 0 0.7 6.7 0 12.4 9.6 0 18.6 3.1 2 1.3 6.4 113.6 9.4 1 19.5 2.4 12 1.5 5.1 4 13.9 8.8 13 21.8 2.0 40 1.3 5.0 26 13.88.8 31 24.6 2.0 67 1.2 4.5 54 13.5 7.3 56 18.2 1.7 117 0.7 5.0 106 13.86.6 116 18.9 1.8

Example 6. Reduction of H₂S Using Performic Acid

Performance of performic acid, PAA 2 (15% peracetic acid, 10% hydrogenperoxide) and PAA 1 (21% peracetic acid, 3.5% hydrogen peroxide) werecompared to triazine, a traditional H₂S scavenger in produced water thatwas spiked with saturated H₂S. In a 500 ml bottle, 250 mL of H₂Ssaturated produced water was added. The samples were allowed toequilibrate by mixing. H₂S concentrations were tested using the Dragertube method. Presence of H₂S changes the color of lead acetate media inthe tube to black thus providing a quantitative way of estimating H₂S inthe head space of each bottle. H₂S was sampled at 0 minute (just priorto addition of reducers/scavengers), at 6 minutes and 60 minutes afteraddition. An untreated bottle was sampled at each of these time pointsto estimate the loss of H₂S due to weathering from the bottle. For thesake of direct comparison, 10 ppm active of each chemistries were addedto the reaction. Rate of H₂S reduction was calculated for each of thechemistries added. As can be observed from the rate of H₂S reduction inFIG. 6, performic acid performs at a rate similar to that of Triazineand comparable to that of PAA 2 (15% peracid/10% peroxide formulation).There is a small portion of H₂S lost from sample bottles due toweathering.

Example 7. Reduction of Iron Sulfide in Produced Water

Iron in iron-sulfide exists as Fe(II). Upon oxidation (with peraceticacid or any other oxidant) Fe(II) becomes Fe (III). Ferrozine is a dyethat specifically binds Fe(II) to produce a purple color that can bemonitored at 593 nm. By quantifying the Fe(II) in the test sample andcomparing untreated against peracetic acid treated samples, theeffectiveness of peracetic acid or performic acid in removing ironsulfide from the water samples can be assessed. Iron (III) oxide ishighly insoluble and precipitates thereby aiding removal.

In a typical test, 1 mL of saturated sodium acetate is added to 3 mL ofwater. This is followed by addition of 450 uL of the test sample (mixedthoroughly to ensure homogeneity). Ferrozine at approximately 20 ppm isadded and the mixture incubated at room temperature for 5 min. A deeppurple color will develop in samples containing Fe (II). The absorbanceof the test samples at 593 are compared to calibration curve obtainedfrom the absorbance readings of iron standards (0 to 500 ppm) preparedfrom iron (III) ICP standards. To measure total iron in the sample theabove reaction should be reduced with freshly prepared ascorbic acid orhydroxylamine solution.

In the produced water used in this analysis, ˜0.03% (300 ppm) (assumedas 100%) of iron is present as iron sulfide. After treatment withperacetic acid PAA 2, PAA 1 or performic acid for 1 hour, as shown inFIG. 7, a complete elimination of iron sulfide is observed, indicatingthat both peracetic and performic acids can be used for the iron-sulfidetreatments in produced water.

Example 8. Water Clarification

One of the potential benefits of oxidizers in treating produced watersis its ability to clarify water by oxidizing contaminants. We evaluatedthe performance of PAA 2, PAA 1 and performic acids in the presence ofcoagulants and flocculants in its ability to improve clarity of water.For water clarification, 100 ppm of coagulant was added to producedwater. This mixture was allowed to mix for 2 min. This was followed bythe addition of 30 ppm active PAA from PAA 2, PAA 1 and 10 ppm active ofperformic acid respectively. After oxidation by these peracidsflocculants 71301 at 2 ppm concentration was used. The samples wereallowed to separate for 15-20 minutes at room temperature. Five (5) mLof sample was carefully taken from the untreated and peracid treatedsamples and % transmittance was measured. Clearer the water higher thetransmittance value.

As shown in FIG. 8, performic acid at 10 ppm active provides claritythat is comparable to PAA 1 (21% peracid/3.5% peroxide) at 30 ppmactive. Untreated water however does not transmit light. Pictures of preand post water clarification are also shown in FIG. 9.

Example 9. Dissolved Oxygen

The purpose of this study is to determine increase in dissolved oxygenin produced-water upon treatment with PAA 2, PAA 1, and PFA. When dosedinto produced water at or below demand concentrations, both chemistriesdo not significantly alter dissolved oxygen content. However, uponaddition of excess of PAA 2 and PAA 1 beyond consumption rate, there isan increase in the total dissolved oxygen in the system. However,addition of PFA decreases the total oxygen content in the samples.

Fifty (50) mL of produced water was treated with PAA 2 or PAA 1. Dosagewas based on demand concentration determined by performing a consumptionstudy on the sample. All the experiments were performed at the sametemperature (20.8 to 21.1° C.) and mixing rate. After the addition ofperacetic acid to the appropriate dosage, the sample was allowed to mixfor 1 minute. SPER scientific dissolved oxygen probe was used for allexperiments. Prior to use, the probe was calibrated and the ambientoxygen reading was 20.9%. The probe was allowed to sit in the solutionfor 30 seconds during which the data were recorded. The values reportedin the tables below are the ‘stabilized’ value after 30 seconds ofequilibration of the probe in the solution. For each sample, dissolvedoxygen prior to treatment was determined. This can be used as thebaseline. The values indicated in the table are an average of twoindependent experiments but using the same produced water.

Example 10. Treatment of Produced Water with PAA 2

Based on the consumption study, the demand for PAA 2 was determined tobe 950 ppm product (142.6 ppm active) as shown in Table 11. The baseline02 measurement was determined to be 9.0 after equilibrating the producedwater under ambient conditions. Any increase in the dissolved oxygenfrom this baseline value can therefore be assumed to be caused byperacetic acid or peroxide components of PAA 2. Subtracting the baselineany the increase in dissolved oxygen is shown in Table 12.

TABLE 11 Concentration (ppm) of oxygen detected in PAA 2 treatedproduced water De- ppm of ppm of ppm of Expt1 Expt2 avg stddev mand PAA2 PAA H₂O₂ ppm O₂ ppm O₂ ppm O₂ ppm 0.0 0.0 0.0 0.0 9.0 8.9 9.0 0.1 0.5475.0 71.3 47.5 9.0 8.9 8.9 0.1 1.0 950.0 142.6 95.0 9.6 9.7 9.7 0.1 1.51425.0 214.0 142.5 11.1 10.6 10.8 0.3 2.0 1900.0 285.3 190.0 11.3 10.510.9 0.6 4.0 3800.0 570.6 380.0 14.0 14.2 14.1 0.1 8.0 7600.0 1141.1760.0 21.0 21.5 21.0 0.4

TABLE 12 Increase from baseline of Oxygen (in ppm) of PAA 2 treatedproduced water De- ppm of ppm of ppm of Expt1 Expt2 avg stddev mand PAA2 PAA H₂O₂ ppm O₂ ppm O₂ ppm O₂ ppm 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.5475.0 71.3 47.5 −0.1 −0.1 −0.05 0.0 1.0 950.0 142.6 95.0 0.6 0.8 0.7 0.11.5 1425.0 214.0 142.5 2.1 1.7 1.9 0.3 2.0 1900.0 285.3 190.0 2.3 1.62.0 0.5 4.0 3800.0 570.6 380.0 5.0 5.3 5.0 0.2 8.0 7600.0 1141.1 760.012.0 12.6 12.3 0.4

The total dissolved oxygen increases with increased dosage of PAA 2. At50% demand dosage, the increase in dissolved oxygen is insignificant.However at 100% demand and beyond an increase in total dissolved oxygenbeyond the baseline can be measured. The small increase in dissolvedoxygen may be due to an error in the estimation of the demandconcentration.

Example 11. Treatment of Produced Water with PAA 1

Based on the consumption study the demand for PAA 1 was determined to be825 ppm as shown in Table 13 below. The baseline 02 measurement wasdetermined to be between 8.0 and 9.0 after equilibrating the producedwater under ambient conditions. Any increase in the dissolved oxygenfrom this baseline value can therefore be assumed to be caused byperacetic acid or peroxide component of PAA 1. Subtracting the baselineppm, the increase in dissolved oxygen is indicated in Table 14.

TABLE 13 Concentration (ppm) of oxygen detected in PAA 1 treatedproduced water De- ppm of ppm of ppm of Expt1 Expt2 avg stddev mand PAA1 PAA H₂O₂ ppm O₂ ppm O₂ ppm O₂ ppm 0.0 0.0 0.0 0.0 9.0 8.0 8.5 0.7 0.5412.5 82.5 12.4 8.8 8.0 8.4 0.6 1.0 825.0 165.0 24.8 9.0 7.9 8.4 0.8 1.51237.5 247.5 37.2 9.0 8.3 8.6 0.5 2.0 1650.0 330.0 49.5 9.7 9.2 9.4 0.44.0 3300.0 660.0 99.1 13.8 14.0 13.9 0.1 8.0 6600.0 1320.0 198.2 19.019.2 19.1 0.1

TABLE 14 Increase from baseline of Oxygen (in ppm) of PAA 1 treatedproduced water De- ppm of ppm of ppm of Expt1 Expt2 avg stddev mand PAA1 PAA H₂O₂ ppm O₂ ppm O₂ ppm O₂ ppm 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.5412.5 82.5 12.4 −0.2 −0.1 −0.1 0.1 1.0 825.0 165.0 24.8 0.0 −0.2 −0.10.1 1.5 1237.5 247.5 37.2 0.0 0.3 0.1 0.2 2.0 1650.0 330.0 49.5 0.7 1.20.9 0.4 4.0 3300.0 660.0 99.1 4.8 6.0 5.4 0.8 8.0 6600.0 1320.0 198.210.0 11.2 10.6 0.9

At and below 100% demand, the total dissolved oxygen does not increase.As was seen with PAA 2 there is a dosage dependent increase in dissolvedoxygen suggesting that both peracetic acid and peroxide contribute tothe total dissolved oxygen in solution.

Example 12. Treatment of Produced Water with Performic Acid

Concentration (ppm) of oxygen detected in performic treated producedwater is shown in Table 15 below. The baseline 02 measurement wasdetermined to be between 8.0 and 9.0 after equilibrating the producedwater under ambient conditions. Subtracting the baseline ppm, theincrease in dissolved oxygen is indicated in Table 16 below.

TABLE 15 Concentration (ppm) of oxygen detected in performic treatedproduced water ppm of ppm of ppm of Expt1 Expt2 avg stddev prod PFA H₂O₂ppm O₂ ppm O₂ ppm O₂ ppm 0.0 0.0 0.0 8.0 8.6 8.3 0.4 500.0 29.0 0.0 5.45.4 5.4 0.0 1000.0 58.0 0.0 6.2 4.9 5.5 0.9 1500.0 87.0 0.0 6.5 5.2 5.80.9 2000.0 116.0 0.0 6.3 5.2 5.8 0.8 4000.0 232.0 0.0 5.8 4.7 5.3 0.88000.0 464.0 0.0 6.5 5.1 5.8 1.0

TABLE 16 Increase from baseline of oxygen (in ppm) of performic treatedproduced water ppm of ppm of ppm of Expt1 Expt2 avg stddev Prod PFA H₂O₂ppm O₂ ppm O₂ ppm O₂ ppm 0.0 0.0 0.0 0 0 0 0 500.0 29.0 0.0 −2.6 −3.2−2.9 0.4 1000.0 58.0 0.0 −1.8 −3.7 −2.8 1.3 1500.0 87.0 0.0 −1.5 −3.4−2.5 1.3 2000.0 116.0 0.0 −1.7 −3.4 −2.6 1.2 4000.0 232.0 0.0 −2.2 −3.9−3.1 1.2 8000.0 464.0 0.0 −1.5 −3.5 −2.5 1.4

Performic acid addition decreased the total dissolved oxygen in thesamples. This is in stark contrast to that observed in samples treatedwith peracetic acid as shown in FIG. 10. Without wishing to be bound byany particular theory, one possible explanation to the decrease in totaldissolved oxygen is that the breakdown products of performic acidformulation include CO₂ that displaces oxygen from the produced watersamples. To test this hypothesis, CO₂ Drager tubes were obtained andheadspace of the sample that was treated with performic acid analyzed.As can be seen from FIG. 11 wherein the darkened color as shown in greyscale (purple color during testing) indicates generation of CO₂,addition of performic acid to produced water produces CO₂ suggestingthat the breakdown products of performic acid produce CO₂ instead ofoxygen like that observed in peracetic acid. This feature may make thisproduct useful for application that is sensitive to the presence ofoxygen, e.g., offshore applications.

Example 13. Comparison of Corrosion Profiles PAA 2, PAA 1 and PerformicAcid on Carbon Steel

Corrosion rate in MPY (millimeters per year) were determined for carbonsteel coupons in produced water treated with peracids. Prior totreatment, consumption of peracids for complete oxidation ofiron-sulfide, microbial kill etc. was determined for each composition.In a bubble cell test, carbon steel coupons were submerged in producedwater that was purged with CO₂. This was done for 3-4 hours to establisha baseline. After the baseline corrosion rate was stabilized, PAA 2, PAA1 or performic acid was added to produced water at the previouslydetermined demand concentration. Corrosion rate of the coupon in peracidtreated produced water were monitored for 19 hours. The rates ofcorrosion are shown In FIG. 12.

As shown In FIG. 12, PAA 2 has the highest corrosion rate, followed byPAA 1. Among the three peracid composition tested, performic acidexhibits the lowest corrosion rate. Bubble cell testing is not acompletely closed system. In addition, iron in the carbon steel couponsis oxidized to iron oxide or iron carbonate both of which lead topassivation of the electrode over time thus leading to a decreased(observed) corrosion rate in system. However in field systems any carbonsteel coupons will encounter corrosion rates that are highest observedin a particular treatment.

PAA 2 and PAA 1 are peracetic acid/hydrogen peroxide compositions. Alower ratio of peracetic acid/hydrogen peroxide in PAA 2 (ratio of 1.5)shows significantly higher corrosion rate than PAA 1 (Peraceticacid/peroxide ratio of about 7). In performic acid system, there was noobserved hydrogen peroxide. Therefore the corrosion rate because ofoxygen in the system is negligible. This observation alone provides asignificant advantage for performic acid over peracetic acid systems indecreasing the total corrosion rates in treatment systems.

Example 14. Formation of High Peracid to Hydrogen Peroxide Ratio inReactions Less than 2 Hours is Unique to Equilibrium Between Formic Acidand Hydrogen Peroxide

To determine if formation of a high peracid to hydrogen peroxide ratiois unique to the equilibrium reaction between formic acid and hydrogenperoxide, control experiments were performed using the same formulationbut acetic acid instead of formic acid in a control reaction. The Tables17 and 18 below list the percentage of performic or peracetic acids andresidual hydrogen peroxide that were detected.

TABLE 17 Performic acid formation from a mixture of formic acid andhydrogen peroxide Time(min.) Wt (g) EP1(ml) EP2(ml) % PFA % H₂O₂ 0 0.00.0 5 1.14 6.2 15.0 1.7 1.3 14 0.46 6.1 6.3 4.2 0.1 25 0.48 7.5 7.5 5.00.0 48 0.32 5.0 5.0 5.0 0.0

TABLE 18 Peracetic acid formation from a mixture of acetic acid andhydrogen peroxide Time (min.) Wt (g) EP1(ml) EP2(ml) % POAA % H₂O₂ 0 0.00.0 6 0.8 0.2 10.6 0.1 2.3 23 1.0 0.4 14.0 0.2 2.3 89 0.7 0.1 8.9 0.12.1

Example 15. Use of Corrosion Inhibitor(s)

Performic acid introduces less corrosion to the carbon steel systemsthan peracetic formulations. Nevertheless, even the lower, acidcorrosion, introduced by performic acid (PFA) can be mitigated by usingone of the exemplary corrosion inhibitor compounds listed in Table 19below. These compounds can be used either alone or as a mixture. Theexemplary phosphate esters, diacids, quat amines, imidazoline, alkylpyridine, phosphonium salts and derivatives of the above mentioned classof compounds can be added in the formulation from about 1 ppm to about50,000 ppm either in the formulation components (e.g., formic acid,peroxide) or can be added separately prior to PFA treatment, with PFAtreatment or post PFA treatments. Some of these compounds also exhibitsynergy in the total kill of microbes with performic acid. Addition ofthe corrosion inhibitor(s) can be performed either pre, with or posttreatment of waters with performic acid. In addition, the listedcompounds can also be mixed into one of the reagents used in theproduction of performic acid.

TABLE 19 Exemplary class of compounds and representative raw materialsused for mitigation of corrosion caused by performic acid Corro- sionInhib- Class of itor Formulation Active(s) compound CI 1Benzyl-dimethyl-dodecyl-ammonium chloride Quat. AmineBenzyl-dimethyl-tetradecyl-ammonium chlorideBenzyl-dimethyl-hexadecyl-ammonium chlorideBenzyl-dimethyl-octadecyl-ammonium chloride CI 2Benzyl-dimethyl-dodecyl-ammonium chloride Quat. AmineBenzyl-dimethyl-tetradecyl-ammonium chlorideBenzyl-dimethyl-hexadecyl-ammonium chlorideBenzyl-dimethyl-octadecyl-ammonium chloride CI 3 Tall oil,diethylenetriamine imidazoline Imidazoline CI 4 Fatty acids, tall-oil,reaction products with n- Imidazoline (2-aminoethyl)-1,2-ethanediamine &2-propenoic acid CI 5 Ethoxylated-C11-14-iso-, C13-rich, phosphatesPhosphate Ester CI 6 Ethoxylated branched nonylphenol PhosphateEthoxylated branched nonylphenol, phosphates Ester CI 7 Trimeric c18unsat fatty acid Diacids CI 8 Tar bases, quinoline derivs., benzylchloride- Alkyl quaternized pyridine; Haloalkyl heteropoly- cycle saltCI 9 Benzyl chloride Benzyl, Benzyl-dimethyl-dodecyl-ammonium chlorideAlkylquat Benzyl-dimethyl-tetradecyl-ammonium chloride with scaleBenzyl-dimethyl-hexadecyl-ammonium chlorideBenzyl-dimethyl-octadecyl-ammonium chloride CI 10 Tributyl TetradecylPhosphonium Chloride phosphoni- um chloride CI 11 Diddecyl dimethylammonium carbonate/ Ammonium bicarbonate chloride CI A Quaternaryammonium compound C4-C16 Substituted aromatic amine Alcohols, Fattyacid-amine derivative Aldehydes, Esters CI B Quaternary ammoniumcompound Quat. CI C Quaternary ammonium compound 2-Mercapto- Quat.ethanol 60-24-2 CI D Quaternary Ammonium Chloride Quat. Fatty acid-aminecondensate Quaternary ammonium compound Oxyalkylated Fatty AmineIsopropanol 67-63-0 2-Butoxyethanol 111-76-2 Fatty acid-amine derivativeCyclic amine derivatives, acetate Pyridine, Alkyl Derivs., Acetates

Microbial efficacy of PFA alone (5 ppm active) or PFA (5 ppm active) inconjunction with the compounds (50 ppm product) listed in the Table 20below and in FIG. 13 were tested by measuring the ATP concentration inthe untreated and treated produced water samples (using AccuCounttechnology). Reductions in bacterial numbers were tabulated as % killfor each experiment. The results are represented in FIG. 13 and in Table20. As can be seen from the results, with the exception of CI 8, an alkypyridine compound, all other compounds tested show an increase inbacterial kill indicating that there is a synergy in bacterial kill forPFA when used in conjunction with compounds commonly used for corrosionmitigation.

TABLE 20 Percentage kill of microorganisms in produced water prior toand after treatment with Performic acid Treatment % Kill Untreated 0.0PFA 87.9 CI 6 + PFA 94.8 CI 10 + PFA 94.0 CI 9 + PFA 94.0 CI 8 + PFA83.3 CI 7 + PFA 91.9 CI 5 + PFA 99.4 CI 3 + PFA 99.0 CI 4 + PFA 92.9 CI1 + PFA 97.9 CI 2 + PFA 98.8

In addition to bacterial kill, corrosion profiles of PFA and PFA withcorrosion inhibitors were tested on a carbon steel coupon (C1018) in abubble cell apparatus. The results were monitored continuously andcorrosion rates at 2, 8 and 19 hours are shown in Table 21 below. PFAwas added to all the tests at a concentration of 20 ppm active. Exceptfor the control cell (PFA), corrosion inhibitors at 50 ppm productconcentration was added to all the other cells. Corrosion rates weremonitored continuously. As indicated in Table 21, corrosion rate oncarbon steel coupons increase from a baseline of 32.3 MPY to 236.3 MPYby 2 hours post addition of PFA. With the exceptions of CI 7, CI 5, CI3, CI 6; all other compounds decrease the rate of corrosion caused byPFA.

TABLE 21 Corrosion caused by performic acid can be mitigated by theaddition of the compounds listed in Table 20. After dosing baseline 2hrs 8 hrs 19 hrs (MPY) (MPY) (MPY) (MPY) PFA 32.3 236.2 243.1 419.4 CI6 + PFA 16.8 25.7 32.0 31.5 CI 10 + PFA 41.9 19.8 14.0 14.4 CI 9 + PFA58.4 5.6 4.8 3.7 CI 8 + PFA 90.2 29.5 51.3 89.8 CI 7 + PFA 19.5 249.6381.2 553.6 CI 5 + PFA 61.7 77.3 151.0 147.2 CI 3 + PFA 27.3 48.0 82.384.8 CI 4 + PFA 31.7 17.8 19.5 4.8 CI 1 + PFA 44.6 18.1 11.1 10.3 CI 2 +PFA 114.0 86.7 33.5 21.9

MPY in Table 21 above indicates the rate of corrosion (millimeters peryear). Higher MPYs indicate increased corrosion. It can be observed fromthe Table 21 above that there is a significant reduction in the overallMPY after 2, 8 and 19 hours after the addition of some of the corrosioninhibitors.

Example 16. Exemplary Methods of Generating Peroxyformic Acid

Peroxyformic acid generation at room temperature was evaluated using astabilizing agent as shown in Table 22 and FIG. 14.

TABLE 22 Peroxyformic acid with a stabilizing agent and without acatalyst. weight % Formic acid (98%) 20.0 92.17 Dipicolonic acid 0.00250.01 H₂O₂ (35%) 1.7 7.83 Total 21.7 100 Performic acid 4.63 peroxide0.12

Increase in temperatures resulted in a further increase in the kineticsof formation of performic acid utilizing the formulation of Table 22 asshown in FIG. 15.

Example 17. Optimization of Generating Peroxyformic Acid Using LowHydrogen Peroxide Formulations

Peroxyformic acid generation under ambient temperature was evaluatedusing a catalyst (Dequest, MSA or phosphoric acid at differentconcentrations) as shown in Table 23 and FIG. 16.

TABLE 23 Low H₂O₂ PFA-1 (original) Low H₂O₂ PFA-2 Composition % % Formicacid (98%) 90.17 85.67 H₂O₂ (35%) 7.83 12.83 H₂O₂ (50%) 0 0 MSA (70%)0.0 1.5 H₃PO₄ (75%) Total 100 100 PFA % 4.88 7.50 H₂O₂ % 0.13 0.20

Example 18. Optimization of Generating Peroxyformic Acid Using Catalysts

Peroxyformic acid generation under ambient temperature was evaluatedusing a catalyst (Dequest 2010) at different concentrations as shown inFIG. 17. As shown an increase in peroxyformic generation is observed atincreasing concentrations of the Dequest 2010 catalyst.

Peroxyformic acid generation under ambient temperature was evaluatedusing a catalyst (MSA (methyl sulfonic acid)) at differentconcentrations as shown in FIG. 18. As shown an increase in peroxyformicgeneration is observed employing the catalyst with slight difference inperoxyformic generation at increasing concentrations of the MSAcatalyst.

The effect of temperature on the formation of performic acid in thepresence of the MSA catalyst was evaluated as shown in FIG. 19. A 3%concentration of MSA was evaluated at ambient/room temperature, 50° C.and 4.4° C.

The stability of performic acid in the presence of different catalystsat room temperature was further evaluated as shown in FIG. 20.

Example 19. Use of Catalysts and Corrosion Inhibitor(s) in GeneratingPeroxyformic Acid

Peroxyformic acid was generated in the presence of catalysts and variouscorrosion inhibitors as set forth in Table 19. A premix of formic acid,catalyst and corrosion inhibitor was formed and a second compound ofonly hydrogen peroxide were combined to in the amounts shown in Table24.

TABLE 24 Generation of PFA in the presence of various corrosioninhibitors. Composition 1 2 3 4 CI 2 0.0 1.5 0.0 0.0 CI 4 1.5 0.0 0.00.0 CI 1 0.0 0.0 1.5 0.0 CI 11 0.0 0.0 0.0 3.0 Formic acid (97%) 82.5782.57 82.57 81.07 H₂O₂ (35%) 12.83 12.83 12.83 12.83 MSA (70%) 3 3 3 3DPA 0.1 0.1 0.1 0.1 Total 100 100 100 100

All three evaluated corrosion inhibitors generated performic acidwithout any negative interaction (Composition 4 is control without CI)as shown in Table 25. However, stability of the formulation was impactedon the type of corrosion inhibitor added to the formulation. CI 11provided the best stability (commercially available ammoniumcarbonate/bicarbonate corrosion inhibitor).

TABLE 25 Performic acid generation using formulations of Table 24. %Performic Time (min.) 1 2* 3* 4 5 6.69 6.67 6.71 6.28 10 6.72 6.59 6.626.62 20 6.67 6.07 6.20 6.73 30 6.67 5.62 5.56 6.70 *Hypochloridegenerated.

Example 20. Use of Premix Formulations for Formic Acid for GeneratingPerformic Acid with Hydrogen Peroxide

Formulations using 85% formic acid final formula and 32% peroxide in theformulation were evaluated using phosphoric acid, PEG or Glycerin asdiluent and CI 11 as a corrosion inhibitor as shown in Table 26 and 27(Combination of premixes with peroxide).

TABLE 26 Premix Premix Premix Premix Premix Premix C (25-3) D (25-4) E(25-5) F (25-6) 25-7 25-8 % % % % % % Formic 89.66 89.66 87.37 87.3787.37 87.37 acid (97%) Glycerin 0.00 3.45 5.74 0 0.00 0.00 (99.5%) MSA6.89 3.45 3.45 6.89 3.45 3.45 (70%) CI 11 3.45 3.45 3.45 3.45 3.45 3.45Phos- 0 0 0 2.29 5.73 0 phoric acid (75%) PEG 0 0 0 0.00 0.00 5.74 Total100.00 100.00 100.00 100.00 100.00 100.00

TABLE 27A Material 26-1 26-2 26-3 26-4 26-5 27-1 27-2 27-3 28-1 28-228-3 28-4 28-5 Premix C 87.17 89.17 91.17 92.17 93.17 0 0 0 0 0 0 0 0(25-3) Premix D 0 0 0 0 0 87.17 89.17 91.17 0 0 0 0 0 (25-4) Premix E 00 0 0 0 0 0 0 87.17 89.17 91.17 92.17 93.17 (25-5) Premix F 0 0 0 0 0 00 0 0 0 0 0 0 (25-6) Premix 0 0 0 0 0 0 0 0 0 0 0 0 0 25-7 Premix 25-8H2O2 12.83 10.83 8.83 7.83 6.83 12.83 10.83 8.83 12.83 10.83 8.83 7.836.83 (32%) Total 100 100 100 100 100 100 100 100 100 100 100 100 100

TABLE 27B Material 29-3 29-4 29-5 30-3 30-4 30-5 31-3 31-4 31-5 Premix C0 0 0 0 0 0 0 0 0 (25-3) Premix D 0 0 0 0 0 0 0 0 0 (25-4) Premix E 0 00 0 0 0 0 0 0 (25-5) Premix F 91.17 92.17 93.17 0 0 0 0 0 0 (25-6)Premix 0 0 0 91.17 92.17 93.17 25-7 Premix 91.17 92.17 93.17 25-8 H2O28.83 7.83 6.83 8.83 7.83 6.83 8.83 7.83 6.83 (32%) Total 100 100 100 100100 100 100 100 100

Example 21. Oxygen Release

One of the advantages of performic acid is the release of zero oxygen intreatment systems. This is in sharp contrast to peracetic acid. Oxygenrelease was monitored by dissolved oxygen probes or an orbisphere (DOmonitor).

Treatment in Produced Water

Formulation containing methyl sulfonic acid (no corrosion inhibitor) andtreatment in produced water were evaluated in PAA 2 (15% Peraceticacid/10% peroxide), PAA 1 (21% peracetic acid, 3.65% peroxide) and PFA(7.5% peracetic acid, 0.2% peroxide). Oxygen release in formulationsusing 95-98% formic acid and 35% peroxide were evaluated as shown inFIG. 21 showing that performic acid does not introduce oxygen into thetreatment system in contrast with peracetic acid formulations.

Treatment in Sea Water

The formulations were evaluated for oxygen release in sea water with 500ppm of iron at 22° C. The results are shown in FIG. 22.

For measuring oxygen, water was purged with carbon dioxide to displaceall oxygen. Previously determined dosage of the product was added to thetest condition under constant stirring. Oxygen reading was recorded 20sec to 5 min after each addition to allow for equilibrium.

Ratios of PFA to Peroxide Providing No Oxygen Release

From experiments performed in static bubble cells using synthetic seawater the optimal ratio of performic acid to peroxide was determined tobe 5:1 or greater of performic acid: peroxide. At concentrations lowerthan 5:1 ratio the formulations release oxygen. FIG. 23 providescorrosion profiles at different ratios of performic acid to peroxide. Itis observed that ratios of 40:1, 20:1 and 5:1 produce very similarcorrosion profile whereas ratios lower than that oxidize the carbonsteel. Primary corrosion from formulations containing PFA: peroxide of5:1 and higher is from the acid component in the formulation.Formulations with PFA: peroxide lower than 5:1 is primarily due tooxygen.

Corrosion profiles of PFA to peroxide ratios at 40:1, 20:1 and 5:1 arefurther depicted in FIG. 24. The corrosion profiled show that ratios of40:1, 20:1 and 5:1 provide similar corrosion trends to each other. Allthese formulations do not generate any oxygen.

Corrosion Control of the Acid Component of Performic Acid.

Corrosion inhibitors can be added to treatment systems either prior totreatment with performic acid, with the treatment or after treatmentwith performic acid. If a separate corrosion treatment is necessary thefollowing experiments show that pre-treatment is the best option. Theexperiments were performed by immersing a carbon steel corrosion couponin water treated with 200 ppm of active PFA. 50 ppm of corrosioninhibitors was either treated prior to, during the same time or afterperformic acid treatment. Coupons were weighed after 2 weeks intreatment waters at 50 C. Weight loss indicates corrosion and is markedwith an “X” in Table 28. No weight loss indicates complete corrosionprotection and is indicated by an absence of an “X”. Control isuntreated produced water.

TABLE 28 corrosion summary pre with post CI A X X CI B X X CI C X CI D XX CI 1 X X CI 2 X X CI 3 X X CI 4 X X CI 5 X X X CI 7 X X CI 8 X X CI 9X X CI 10-350 X X CI 10-303 X X Control X X X control 2-PW X X X

Based on the initial experiment it was determined that a corrosioninhibitor is best added prior to addition of performic acid to seawater. The Table 29 shows performance of different types of corrosioninhibitor molecules in protecting carbon steel against performic acidcorrosion (PFA: Peroxide of 38:1). MPY indicates corrosion rate.

TABLE 29 2 hrs after dosing 8 hrs after dosing Last hour of testingDosage Baseline % % % Chemical (ppm) (mpy) mpy Protection mpy Protectionmpy Protection Cell 12 CI 2 114.0 86.7 23.9 33.5 70.6 21.9 80.8 Cell 11CI 1 44.6 18.1 59.5 11.1 75.1 10.3 76.9 Cell 10 CI 4 31.7 17.8 43.8 19.538.5 4.8 84.8 Cell 9 CI 3 27.3 48.0 −75.6 82.3 −201.2 84.8 −210.4 Cell 8CI 5 61.7 77.3 −25.3 151.0 −144.9 147.2 −138.7 Cell 7 CI 7 19.5 249.6−1180.9 381.2 −1856.4 553.6 −2741.3 Cell 6 CI 8 90.2 29.5 67.2 51.3 43.189.8 0.4 Cell 5 CI 9 58.4 5.6 90.4 4.8 91.8 3.7 93.6 Cell 4 CI 10 41.919.8 52.7 14.0 66.5 14.4 65.7 Cell 3 CI B 16.8 25.7 −52.6 32.0 −90.131.5 −87.5 Cell 2 PFA 32.3 236.2 −631.1 243.1 −652.3 419.4 −1197.9 Cell1 Ester 140.5 274.7 −95.5 281.9 −100.6 254.1 −80.8Performance of Corrosion Inhibitor in Sea Water and Produced WaterSystems.

200 ppm active of performic acid was added. 50 ppm of corrosioninhibitor was added for corrosion protection. % protection was plottedby comparison of the corrosion rate in the presence of corrosioninhibitor to the corrosion rate with no corrosion inhibitor addition(PFA or PFA-PW) as shown in Table 30.

TABLE 30 3 hrs after dosing 8 hrs after dosing Last hour of testingDosage Baseline % % % Chemical (ppm) (mpy) mpy Protection mpy Protectionmpy Protection CI 10 -PW 5.1 12.2 −139.9 2.2 56.1 1.2 76.0 CI 10 34.725.2 27.6 19.4 44.2 17.7 49.0 CI 9 -PW 4.7 2.5 47.1 2.0 58.6 1.6 65.2 CI9 98.0 4.3 95.6 3.1 96.8 2.7 97.3 CI 4 -PW 3.8 4.4 −17.4 3.2 16.4 2.924.5 CI 4 54.0 37.6 30.4 19.1 64.7 20.1 62.9 CI 1 - PW 5.7 3.9 32.2 2.458.6 2.1 62.8 CI 1 101.7 60.7 40.2 36.3 64.3 28.4 72.0 CI 2 -PW 4.9 2.548.1 1.4 70.3 1.3 73.5 CI 2 87.3 35.7 59.1 15.4 82.4 8.7 90.0 PFA-PW 5.117.2 −237.2 16.7 −228.1 18.4 −261.2 PFA 5.1 545.9 −10666.2 686.9−13447.5 739.4 −14481.9Corrosion Control

As shown in Example 19, corrosion inhibitors can be included in theformulation. Since performic acid equilibrium between formic acid premixand peroxide is fast inline formation of corrosion inhibitor includedperformic acid can afford the corrosion protection without the additionof an external corrosion inhibitor. FIG. 25 shows bubble cell profilesof corrosion inhibition provided by corrosion inhibitor included in theco-formulation as described in Example 19.

As compared to PFA alone all corrosion inhibitors formulated providesignificant corrosion protection compared to the background corrosionrate. The corrosion protection at 2, 8 and 16 hrs is shown in FIG. 26.

Example 22. Biocidal Performance of Performic Acid

The following test system shown in Table 31 was evaluated for logreduction of Pseudomonas aeruginosa.

TABLE 31 Test Systems: Pseudomonas aeruginosa ATCC 15442 Test Substance500 ppm synthetic hard water, pH 7.74 Diluents: Test A. 0.5 ppm PFA: 47μL PFA Concentrate Substances: (0.107% PFA)/99 mL diluent pH 6.71 B. 1.0ppm PFA: 93 μL PFA Concentrate (0.107% PFA)/99 mL diluent pH 6.31 C. 2.0ppm PFA: 185 μL PFA Concentrate (0.107% PFA)/99 mL diluent pH 5.34Exposure 10 minutes and 4 hours Time(s): Neutralizer: 9 mL DE Broth Test25° C. Temperature Plating TGE Medium: Incubation: 35° C. for 48 hours

FIG. 27 shows the results of biocidal efficacy after 10 minutes contactand 4 hours contact showing the beneficially efficacy of performic acidgenerated according to the invention.

Example 23. Biocidal Performance of Performic Acid on Treated ProducedWater

Treatment of produced water with performic acid was evaluated usingperformic acid compositions containing a corrosion inhibitor. As shownin FIG. 28 (grey scale) the lighter color indicates no growth in thewater, whereas the darker shading indicates no growth. Untreated has E5bacteria/mL; 0.5 ppm PFA treated has E3 bacteria/mL. The bacterial bugbottles are specific in supporting growth of acid producing bacteria(APBs). Growth of APB is indicated by a color change from dark to lightcolor (pink to yellow). 1 mL of initial inoculum was diluted 10 times insubsequent bottles. Therefore each bottle indicates a E1 bacteria/mL.Based on the results observed by growth/no growth of bacteria it can beconcluded that PFA treatment results in at least a reduction of 2 log(equivalent of E2 bacteria/mL) bacteria.

Example 24. Biofilm Biocidal Performance

A Pseudomonas biofilm was treated with 50 ppm active of PFA and comparedto efficacy treated with 200 ppm PAA. Pseudomonas biofilms were grown ina CDC biofilm reactor on a poly carbonate coupons. Appropriateconcentration of the treatment substance were diluted in hardwater at pH7.71 diluent. Test chemicals were exposed for 3 hrs after which theywere treated with 16 mLs of thiosulfate to neutralize any oxidants. Theuntreated control and treated Pseudomonas were plated on a TGE media andincubated at 35° C. for 48 hrs. A 4 hr reduction was monitored by colonycounting of Pseudomonas on plates. Results are shown in FIG. 29demonstrating the beneficially efficacy of PFA generated according tothe invention.

Example 25. Iron Sulfide Oxidation

The extent of oxidation of iron sulfide in water source (produced water)was evaluated using performic acid compared to peracetic acid. As shownin FIG. 30 complete oxidation of iron sulfide in produced water isachieved with performic acid (PFA). This property is similar to thatobserved for peracetic acid also. Iron (II) was measured 30 minutesafter the addition of the oxidant into treated waters.

Example 25. Hydrogen Sulfide Oxidation

Hydrogen sulfide reduction was measured in produced water treated withperformic acid (10 ppm active added to produced water containing 2000ppm of H₂S). 30 ppm active of PAA 2 and PAA 1 were added. 30 ppm activeof Triazine was added as comparison. Triazine chelates H₂S howeverperacid oxidizes H₂S. Concentration of H₂S was measured using a Draggertube by sampling the head space. H₂S containing sample was constantlystirred. Total H₂S indicated below was measured 1 hr. after treatment.The results are shown in FIG. 31.

Example 26. Reduction of E. coli Using Performic Acid Compositions

Nalidixic acid resistant E. coli O157:H7 was used to evaluate theefficacy in treatment with performic acid composition on raw beefbrisket according to the conditions shown in Table 32.

TABLE 32 Test System: Nalidixic acid resistant E. coli O157:H7 TestSubstance Sterile DI Water buffered to pH 9.5 with sodium Diluent:bicarbonate and carbonate Red Meat: Beef flank steak/brisket, cut into 5cm square pieces Inoculation: 100 μl, spot inoculated and then spreadwith a sterile hockey stick Attachment Time: 1 hour at 4° C. Treatment:Dip for 10 minutes, allowing chemistry to drain off of meat for 15seconds before neutralizing (3 samples a time) Neutralizer: 50 mL DEBroth Recovery: Stomached meat in neutralizer for 30 seconds at 230 rpmTest Temperature Ambient Plating Medium: TSA with nalidixic acid (1 ml/Lmedia) Incubation: 35° C. for 48 hours Notes: Ester PFA turned meatwhite/gray during treatment

The micro results are shown in Tables 33-34, demonstrating improvedmicro efficacy (log reduction) achieved from PFA compositions incomparison to POAA.

TABLE 33 Average Exposure Plate Plate Log Standard Log Log TestSubstance Time Count Dilution CFU/ml CFU/cm2 CFU/cm2 Deviation CFU/cm2Reduction 220 ppm POAA, pH 8.86 10 60 10 6.00E+02 1.20E+03 3.08 0.092.98 1.06 minutes 45 10 4.50E+02 9.00E+02 2.95 40 10 4.00E+02 8.00E+022.90 220 ppm POAA + 50 ppm LAS 41 10 4.10E+02 8.20E+02 2.91 0.10 2.991.05 pH 8.88 63 10 6.30E+02 1.26E+03 3.10 45 10 4.50E+02 9.00E+02 2.95180 ppm PFA, pH 8.76 92 10 9.20E+02 1.84E+03 3.26 0.06 3.22 0.83 71 107.10E+02 1.42E+03 3.15 86 10 8.60E+02 1.72E+03 3.24 180 ppm PFA + 50 ppmLAS 103 10 1.03E+03 2.06E+03 3.31 0.04 3.29 0.76 pH 8.79 87 10 8.70E+021.74E+03 3.24 100 10 1.00E+03 2.00E+03 3.30 (2 part PFA-forming) 16 101.60E+02 3.20E+02 2.51 0.22 2.74 1.30 180 ppm PFA, pH 6.61 31 103.10E+02 6.20E+02 2.79 43 10 4.30E+02 8.60E+02 2.93 (2 partPFA-forming) + LAS 26 10 2.60E+02 5.20E+02 2.72 0.26 2.71 1.33 180 ppmPFA + 50 ppm LAS 47 10 4.70E+02 9.40E+02 2.97 pH 6.66 14 10 1.40E+022.80E+02 2.45 LAS 41 100 4.10E+03 8.20E+03 3.91 0.15 3.78 0.27 50 ppmLAS, pH 9.47 31 100 3.10E+03 6.20E+03 3.79 21 100 2.10E+03 4.20E+03 3.62Water Control 27 100 2.70E+03 5.40E+03 3.73 0.06 3.80 DI H₂O Buffered topH 9.5 33 100 3.30E+03 6.60E+03 3.82 35 100 3.50E+03 7.00E+03 3.85Non-treated Controls 61 100 6.10E+03 1.22E+04 4.09 0.06 4.04 59 1005.90E+03 1.18E+04 4.07 47 100 4.70E+03 9.40E+03 3.97 Inoculum Numbers 42100000 4.20E+06 54 100000 5.40E+06 Background Numbers 25 0 2.50E+02 46 04.60E+02

TABLE 34 Micro Efficacy Results Summarized Log Test Substance Reduction220 ppm POAA, pH 8.86 1.06 220 ppm POAA + 50 ppm LAS pH 8.88 1.05 (2part PFA-forming) 180 ppm PFA, pH 6.61 1.30 (2 part PFA-forming) + LAS180 ppm PFA + 1.33 50 ppm LAS pH 6.66

Example 27. Bactericidal Activity of PFA Versus POAA

Staphylococcus, Enterococcus and Pseudomonas pathogens were used toevaluate the micro efficacy of PFA in comparison to POAA. The testmethods are shown in Table 35 and the results are shown in Tables 36-39.

TABLE 35 Test Parameters Test Systems: Staphylococcus aureus ATCC 6538(0.217 A @ 620 nm) Enterococcus hirae ATCC 10541 (0.184 A @ 620 nm)Pseudomonas aeruginosa ATCC 15442 (0.191 A @ 620 nm) Test Substances:PFA (9.86% PFA) POAA (14.95% POAA) Test Substance EN Synthetic HardWater, pH 7.04 Diluent: Test Substance 20 ppm PFA × 1.25 pH 6.61Dilutions: 30 ppm PFA × 1.25 pH 6.74 50 ppm PFA × 1.25 pH 6.60 25 ppmPOAA (molar equivalent to 20 ppm PFA) × 1.25 pH 6.73 38 ppm POAA (molarequivalent to 30 ppm PFA) × 1.25 pH 6.74 62 ppm POAA (molar equivalentto 50 ppm PFA) × 1.25 pH 6.98 Interferring Dirty Conditions BovineAlbumin Solution Substance: (3 g/L) + sheep erythrocytes ExposureTime(s): 5 minutes Neutralizer: 8 mL DE Broth + 1 mL sterile water TestTemperature: 20° C. Plating Medium: Oxoid TSA Incubation: 35° C. for 48hours

TABLE 36 Results Exposure Average Log₁₀ Log₁₀ Test Substance TimeOrganic Soil CFU/mL Growth Reduction 20 ppm PFA × 5 minutes Dirty <140<2.15 >5.15 1.25 pH 6.61 Conditions 30 ppm PFA × (High <140 <2.15 >5.151.25 pH 6.74 concentration 50 ppm PFA × Bovine <140 <2.15 >5.15 1.25 pH6.60 Albumin 24.8 ppm POAA × Solution + 1.77E+05 5.25 2.05 1.25 pH 6.73sheep 37.6 ppm POAA × erythrocytes) <140 <2.15 >5.15 1.25 pH 6.90 62.4ppm POAA × <140 <2.15 >5.15 1.25 pH 6.98 Test Mixture Inoculum Numbers(N_(o)) 1.97E+07 7.30 S. aureus ATCC 6538 1.97E+08 Test SuspensionNumbers (N) Validation Test Suspension Numbers (N_(v)) 5.70E+02 ControlMixture Inoculum Numbers (N_(vo)) 5.70E+01 Control A Dirty 5.60E+01Conditions Control B 7.40E+01 Control C-A Dirty 5.90E+01 Control C-BConditions 6.00E+01

TABLE 37 Results Exposure Average Log₁₀ Log₁₀ Test Substance TimeOrganic Soil CFU/mL Growth Reduction 20 ppm PFA × 5 minutes Dirty6.30E+03 3.80 3.46 1.25 pH 6.61 Conditions 30 ppm PFA × (High 2.15E+022.33 4.92 1.25 pH 6.74 concentration 50 ppm PFA × Bovine <140<2.15 >5.10 1.25 pH 6.60 Albumin 24.8 ppm POAA ×Solution + >3.30E+05  >5.52 <1.74 1.25 pH 6.73 sheep 37.6 ppm POAA ×erythrocytes) 9.25E+03 3.97 3.29 1.25 pH 6.90 62.4 ppm POAA × <140<2.15 >5.10 1.25 pH 6.98 Test Mixture Inoculum Numbers (N_(o)) 1.80E+077.26 E. hirae ATCC 10541 1.80E+08 Test Suspension Numbers ValidationTest Suspension Numbers (N_(v)) 4.30E+02 Control Mixture InoculumNumbers (N_(vo)) 4.30E+01 Control A Dirty 7.70E+01 Conditions Control B6.60E+01 Control C-A Dirty 4.60E+01 Control C-B Conditions 5.30E+01

TABLE 38 Results Exposure Average Log₁₀ Log₁₀ Test Substance TimeOrganic Soil CFU/mL Growth Reduction 20 ppm PFA × 5 minutes Dirty <140<2.15 >5.22 1.25 pH 6.61 Conditions 30 ppm PFA × (High <140 <2.15 >5.221.25 pH 6.74 concentration 50 ppm PFA × Bovine <140 <2.15 >5.22 1.25 pH6.60 Albumin 24.8 ppm POAA × Solution + <140 <2.15 >5.22 1.25 pH 6.73sheep 37.6 ppm POAA × erythrocytes) <140 <2.15 >5.22 1.25 pH 6.90 62.4ppm POAA × <140 <2.15 >5.22 1.25 pH 6.98 Test Mixture Inoculum Numbers(N_(o)) 2.35E+07 7.37 P. aeruginosa ATCC 15442 2.35E+08 Test SuspensionNumbers Validation Test Suspension Numbers (N_(v)) 5.05E+02 ControlMixture Inoculum Numbers (N_(vo)) 5.05E+01 Control A Dirty 8.40E+01Conditions Control B 9.00E+01 Control C-A Dirty 5.50E+01 Control C-BConditions 4.30E+01

TABLE 39 Passing Requirements & Results Passing Requirements per EN1276: S. aureus E. hirae P. aeruginosa N is between 1.5 × 10⁸ CFU/mL N =1.97 × 10⁸ N = 1.80 × 10⁸ N = 2.35 × 10⁸ and 5.0 × 10⁸ CFU/mL N_(vo) isbetween 30 and 160 CFU/mL N_(vo) = 57 N_(vo) = 43 N_(vo) = 51 ControlsA, B, C are equal to or YES YES YES greater than 0.5 × N_(vo) A greaterthan 5 log₁₀ reduction (R) 20 ppm PFA − 20 ppm PFA − 20 ppm PFA − isachieved within the 5 minute R = >5.15 R = 3.46 R = >5.22 contact time:30 ppm PFA − 30 ppm PFA − 30 ppm PFA − R = >5.15 R = 4.92 R = >5.22 50ppm PFA − 50 ppm PFA − 50 ppm PFA − R = >5.15 R = >5.10 R = >5.22 25 ppmPOAA − 25 ppm POAA − 25 ppm POAA − R = 2.05 R = <1.74 R = >5.22 38 ppmPOAA − 38 ppm POAA − 38 ppm POAA − R = >5.15 R = 3.29 R = >5.22 62 ppmPOAA − 62 ppm POAA − 62 ppm POAA − R = >5.15 R = >5.10 R = >5.22

Example 28. Summary of Fungicidal and Sporicidal Activity of PFA

Various pathogens were used to evaluate the broad micro efficacyspectrum of PFA according to the present invention. The test method,substance and results are shown in Table 40.

TABLE 40 Micro Efficacy Test Parameters and Results Test Test PassingMethod Substance Test Organisms Requirement Result EN 450 ppm PFA P.aeruginosa 5 log PASS 13727 pH 6-7 ATCC 15442 reduction Staph. AureusPASS ATCC 6538 Enterococcus PASS hirae ATCC 10541 EN Canidia albicans 4log PASS 13624 ATCC 10231 reduction Aspergillus PASS brasiliensis ATCC1604 EN Bacillus subtilis 3 log PASS 13704 ATCC 6633 reduction ENPoliovirus 4 log PASS 14476 reduction

Example 29. Low Temperature, Low Oxygen Performance of PFA

Micro efficacy of PFA according to the present invention was evaluatedunder low temperature, low oxygen conditions employing the formulationof Table 41.

TABLE 41 Composition % Formic acid 80-90 Hydrogen peroxide (35%) 10-15Dequest 2010 (60%) 0.1-5   Total 100 PFA % 7.5 Hydrogen peroxide % 0.2

The log reduction of L. monocytogenes (ATCC 19114, 19116 and 4594) wereevaluated at low temperature (4° C.) comparing peroxyacetic acid to theperoxyformic acid generated according to the formulation shown in Table41. The results are shown in FIG. 32 comparing disinfectant efficacyafter a 1 minute contact exposure to the disinfectants.

As shown, the disinfectant efficacy of the POAA significantly decreasesat the lower temperature, such as used in brewery and other relatedapplications. Beneficially, the disinfectant efficacy of the in situgenerated peroxyformic acid does not decrease. As a result, theperformic acid generated has a great fit for application in breweryplants. The exceptional antimicrobial efficacy of performic acid at lowtemperature meets the requirement of cold temperature environment ofbrewery operations, while common biocides including peroxycarboxylicacids such as peracetic acids will suffer the efficacy lose under lowtemperatures. In addition, formic acid that always coexists withperformic acid is a very efficient acidulant, which will helpprevent/dissolve beer stone, thus eliminate the additional acid wash. Asa further benefit the performic acid composition has very high performicacid to H₂O₂ ratio, which practically eliminates the O₂ that couldpotentially introduced to the liquid being processed (i.e. beer) andinterfere with the organoleptic effects and negative taste effects.

The detailed description set-forth above is provided to aid thoseskilled in the art in practicing the present invention. However, theinvention described and claimed herein is not to be limited in scope bythe specific embodiments herein disclosed because these embodiments areintended as illustration of several aspects of the invention. Anyequivalent embodiments are intended to be within the scope of thisinvention. Indeed, various modifications of the invention in addition tothose shown and described herein will become apparent to those skilledin the art from the foregoing description which does not depart from thespirit or scope of the present inventive discovery. Such modificationsare also intended to fall within the scope of the appended claims.

All publications, patents, patent applications and other referencescited in this application are incorporated herein by reference in theirentirety for all purposes to the same extent as if each individualpublication, patent, patent application or other reference wasspecifically and individually indicated to be incorporated by referencein its entirety for all purposes. Citation of a reference herein shallnot be construed as an admission that such is prior art to the presentinvention.

What is claimed is:
 1. A method for treating a target water source,which method comprises: contacting a target water source in oil- andgas-field operations with an effective amount of peroxyformic acidcomposition to form a treated target composition, wherein saidperoxyformic acid composition is formed by contacting formic acid andhydrogen peroxide to form a resulting aqueous composition comprisingfrom about 1 wt-% to about 40 wt-% of peroxyformic acid; wherein theperoxyformic acid composition further comprises from about 0.0001 wt-%to about 15 wt-% of a corrosion inhibitor consisting of an ethoxylatedphosphate ester, and a catalyst comprising methanesulfonic acid; whereinbefore said contacting, the ratio between the concentration of saidformic acid (w/v) and the concentration of said hydrogen peroxide (w/v)is about 2 or higher, and the ratio between the concentration of saidperacid (w/w) and the concentration of hydrogen peroxide (w/w) in saidformed resulting aqueous composition reaches about 2 or higher withinabout 2 hours of said contacting; and wherein said contacting lasts forsufficient time to stabilize or reduce microbial population in saidtarget water source or said treated target composition.
 2. The method ofclaim 1, wherein before the contacting, the formic acid is provided in acomposition that comprises formic acid, the composition is an aqueoussolution that comprises formic acid, or formic acid is provided in acomposition that comprises a substance that generates formic acid uponcontact with an aqueous composition.
 3. The method of claim 1, whereinbefore the contacting, the hydrogen peroxide is provided in acomposition that comprises hydrogen peroxide, the composition is anaqueous solution that comprises hydrogen peroxide, or the hydrogenperoxide is provided in a composition that comprises a substance thatgenerates hydrogen peroxide upon contact with an aqueous composition. 4.The method of claim 1, wherein (a) the formic acid provided in a firstaqueous composition is contacted with the hydrogen peroxide provided ina second aqueous composition to form peroxyformic acid in the resultingaqueous composition, or (b) the formic acid provided in a first aqueouscomposition is contacted with a substance that generates hydrogenperoxide upon contact with an aqueous composition provided in a secondsolid composition to form peroxyformic acid in the resulting aqueouscomposition.
 5. The method of claim 1, wherein (a) a substance thatgenerates formic acid upon contact with an aqueous composition providedin a first solid composition is contacted with hydrogen peroxideprovided in a second aqueous composition to form peroxyformic acid inthe resulting aqueous composition, (b) a substance that generates formicacid upon contact with an aqueous composition provided in a first solidcomposition and a substance that generates hydrogen peroxide uponcontact with an aqueous composition provided in a second solidcomposition are contacted with a third aqueous composition to formperoxyformic acid in the resulting aqueous composition, or (c) asubstance that generates formic acid upon contact with an aqueouscomposition and a substance that generates hydrogen peroxide uponcontact with an aqueous composition are provided in a first solidcomposition, and the first solid composition is contacted with a secondaqueous composition to form peroxyformic acid in the resulting aqueouscomposition.
 6. The method of claim 1, which is conducted at atemperature ranging from about −2° C. to about 70° C.
 7. The method ofclaim 1, wherein the catalyst is present in an amount of from about 1wt-% to about 7 wt-%.
 8. The method of claim 1, wherein the resultingaqueous composition comprises from about 1 wt-% to about 20 wt-%peroxyformic acid.
 9. The method of claim 1, wherein the formedresulting aqueous composition comprises the corrosion inhibitor in anamount from about 0.0001 wt-% to about 10 wt-%, wherein the corrosioninhibitor is added to a composition comprising the formic acid, acomposition comprising the hydrogen peroxide or to the resulting aqueouscomposition.
 10. The method of claim 1, wherein the corrosion inhibitorhas a synergistic effect with the peroxyformic acid to stabilize orreduce microbial population in the target water source or the treatedtarget composition and reduces acid corrosion in the target water sourceor the treated target composition.
 11. The method of claim 1, whereinthe corrosion inhibitor reduces corrosion in the target water source orthe treated target composition.
 12. The method of claim 1, wherein theratio between the concentration of the peroxyformic acid (w/v) and theconcentration of the corrosion inhibitor (w/v) used in the method isfrom about 0.01 to about
 100. 13. The method of claim 1, wherein thecorrosion inhibitor has a synergistic effect with the peroxyformic acidto stabilize or reduce microbial population in and/or on the target orthe treated target composition.
 14. The method of claim 1, wherein theperoxyformic acid is used at a concentration from about 0.5 ppm to about1,000 ppm.
 15. The method of claim 1, wherein the treating removeshydrogen sulfide or iron sulfide in the target water source or improvesclarity of the target water source.